#14 - When polar ice caps grow (during ice ages, for example), lighter forms of oxygen

[Administrator]

Complete Question Explanation

Must Be True. The correct answer choice is (D).

Answer choice (A):

Answer choice (B):

Answer choice (C):

Answer choice (D): This is the correct answer choice.

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[lsathelpppp]

Can you explain why B is wrong and D is correct?

[Chandler H]

Can you explain why B is wrong and D is correct?

Hello,

Sure! Answer choice (B) is wrong because we only know that the ice caps grew for 20,000 years and then shrank for 10,000 years. However, we don't know the rate of growing or shrinking, so there's no way for us to know if they were larger at the beginning of that 30,000 year period or not. What if the ice caps grew from (for example) 5 million tons at the beginning of the period, to 15 million tons 20,000 years later, and then shrank back to 10 million tons 10,000 years after that?

Answer choice (D), on the other hand, just tells us that the ice caps grew for 20,000 years, then shrank. We know that because of the information in the stimulus about the sea shellfish. It's much more moderate than other answer choices, which is a good sign.

Does this make sense?