Scientists are Discussing Ways to Remove Excess Carbon Dioxide from the Atmosphere by Increasing the Amount that is Absorbed by Plant Life.

Question: Scientists are discussing ways to remove excess carbon dioxide from the atmosphere by increasing the amount that is absorbed by plant life. One plan to accomplish this is to establish giant floating seaweed farms in the oceans. When the seaweed plants die, they will be disposed of by being burned for fuel.

Which of the following, if true, would indicate the most serious weakness in the plan above?

1. Some areas of the ocean in the Southern Hemisphere do not contain sufficient nutrients to support large seaweed farms.
2. When a seaweed plant is burned, it releases an amount of carbon dioxide compared to the amount it has absorbed in its lifetime.
3. Even if seaweed farms prove efficient, some people will be reluctant to switch to this new fuel.
4. Each year about seven billion tons of carbon dioxide are released into the atmosphere but only about five billion tons are absorbed by plant life.
5. Seaweed farms would make more money by farming seaweed to sell as nutritional supplements than by farming seaweed to sell as fuel.

Answer: B
Explanation: In this GMAT Critical reasoning question, we have to find the option that would indicate the most serious weakness in the plan suggested in the passage.

Let’s go through each of the available options and choose the most suitable one.

Option A: Some areas of the ocean in the Southern Hemisphere do not contain sufficient nutrients to support large seaweed farms.

Option A states that some areas of the ocean in the Southern Hemisphere do not have enough nutrients that can support huge seaweed farms. If that is the case, then the scientists do not have to put the farms in these places. This is irrelevant to the argument presented in the passage that says that seaweed plants can be disposed of by burning for fuel when they die. Since this statement does not talk about how seaweed plants can remove excess carbon dioxide, this statement is not relevant. Option A is incorrect.

Option B: When a seaweed plant is burned, it releases an amount of carbon dioxide compared to the amount it has absorbed in its lifetime.
According to Option B, whenever a seaweed plant is burned, it releases an amount of carbon dioxide compared to the amount it has absorbed in its lifetime. The plan in the passage is to establish seaweed farms that will be used as fossil fuels when burned. But this statement says that burning the seaweeds results in the release of carbon dioxide that is comparable to the Co2 it has absorbed in its lifetime. So, establishing the giant seaweed farms does not make sense. This statement weakens the argument. So, Option B is correct.

Option C: Even if seaweed farms prove efficient, some people will be reluctant to switch to this new fuel.
Option C states that even when seaweed farms prove to be efficient, there will be some people who won’t switch to the new fuel. This statement is entirely out of scope as the passage does not discuss the reluctance of people in accepting the new fuel. Since this option is not relevant to the plan, Option C is incorrect.

Option D: Each year about seven billion tons of carbon dioxide are released into the atmosphere but only about five billion tons are absorbed by plant life.
Option D states that every year, about seven billion tons of Co2 are released but only five billion tons are absorbed by the plants. This statement seems somewhere valid but the scientists never said that the seaweed farms must absorb all the carbon dioxide. The plants won’t absorb all the carbon dioxide, but they will absorb a lot. So, Option D is incorrect.

Option E: Seaweed farms would make more money by farming seaweed to sell as nutritional supplements than by farming seaweed to sell as fuel.
Option E states that seaweed farms can make more money by using the plants to sell nutritional supplements than by using them to sell as fuel. This statement is irrelevant to the passage as the passage nowhere talks about how the seaweed farms would make money. It just talks about how they will help in reducing carbon dioxide in the atmosphere. So, Option E is incorrect.

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