Every adult male woolly monkey is larger than even the largest female woolly monkey. In colonies of woolly monkeys, a...

shunhe on June 23, 2020

Hi @yckim2180,

Thanks for the question! So (A) tells us that size is the primary determinant of relations of dominance among woolly monkeys. But does this have to be true? First of all, the word “primary” should clue us off to this being too strongly worded. Nothing in the paragraph supports that size is the PRIMARY determinant. While it’s true that adult males are larger than females, it’s possible that something else is the primary determinant other than the size, and so we can’t say (A) must be true.

In addition, we have to pick the best answer, and (D) is clearly a better choice since it follows directly from the contrapositive of the second sentence.

Hope this helps! Feel free to ask any other questions that you might have.