The Life Cycle of Stars is on the Order of Billions of Years, Much GMAT Critical Reasoning

Question: The life cycle of stars is on the order of billions of years, much longer than a human life span or even the existence of astrophysics as a discipline. How do we understand the whole stellar life cycle? The Hertzsprung-Russel (HR) diagram sorts stars into different categories depending on their properties. Stellar clusters are collections of stars all of the same age. The location of all the stars in a single stellar cluster on an HR diagram demonstrates the categories for stars at that particular age, and a comparison of plots on the HR diagram for multiple stellar clusters indicates how the different kinds of stars change over the course of their life cycles. The achievement is analogous to that of an imagined intelligent mayfly that, despite being alive for only a single day, is able to figure out the entire human life cycle by observing.

Which of the following most logically completes the passage?

1. The students at a school that goes from kindergarten to the twelfth grade.
2. A gathering of grandparents with their grandchildren.
3. A college with reunions of all classes that graduated N years ago, where N is a multiple of five.
4. The photos of a single living elderly individual, from early childhood to the present day.
5. A hospital with children and adult patients of all ages and a variety of conditions.

“The Life Cycle of Stars is on the Order of Billions of Years, Much Longer than a Human Life Span” – is a GMAT Critical question. This particular GMAT Critical Reasoning topic has been taken from the book ‘501 GMAT Questions’. In this particular topic, candidates need to choose the option that best suits the passage. GMAT critical reasoning tests the logical and analytical skills of the candidates. Critical reasoning in GMAT requires candidates to find the strengths and weaknesses of the argument, or find the logical flaw in the argument.  The GMAT CR section contains 10 -13 GMAT critical reasoning questions out of 36 GMAT verbal questions.

Answer: C

Explanation: This is a GMAT critical reasoning question. We have to select the option that logically completes the above passage.

Let’s go through each option individually and find the one that fits the best to the passage.

Option A: The students at a school that goes from kindergarten to the twelfth grade.
-Option A talks about the students at a school that goes from kindergarten to grade 12. It involves humans in two stages of life; childhood and adolescence. This fails to capture the various groupings of a human life cycle. Humans go through various stages from childhood to adolescence and since this statement does not talk about all the stages, Option A is incorrect.

Option B: A gathering of grandparents with their grandchildren.
-Option B talks about a gathering where the grandparents and their grandchildren are present. It also represents only two stages of life; childhood and old age. There are many stages a person has to undergo between these two stages. Also, in a gathering, these two groups will be mingled and not separated by their age. So, Option B is incorrect.

Option C: A college with reunions of all classes that graduated N years ago, where N is a multiple of five.
-Option C talks about a college that has reunions of all the classes that graduated N years ago and N is a multiple of five. It suggests a college reunion with different graduating classes that are five years apart. There would be groups of 25 years old, 30 years old, 35 years old, 40 years old, and 45 years old. All these groups belong to different stages of the human life cycle. So, we have groups of people at different stages in their lifespan, just like groups of stars at different stages. So, Option C is correct.

Option D: The photos of a single living elderly individual, from early childhood to the present day.
-Option D talks about the photos of a single living elderly person from his childhood to the present day. This statement mentions only one person that is seen in different stages of his life, not groups of people who are in different stages of their lives. The passage mentions the grouping of stars and not individual stars. So, Option D is incorrect.

Option E: A hospital with children and adult patients of all ages and a variety of conditions.
-Option E talks about a hospital that has children and adult patients of all ages and different conditions. It suggests a place with people from different stages of life. But it does not group them together according to their life stages as mentioned in the above passage. So, Option E is incorrect.

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