Hi Emily,

The question stem says that "bromouracil resembles thymine" so instead of a T getting put in to the new strand of DNA it will be inserted.
The question continues to read that once incorporated it makes a conformational change to then resemble Cytosine. In doing so it will base pair with Guanine

so the new antisense will look like: 3'-CCGCABGC-5'
This antisense will code for the sense: 5'-GGCGTGCG-3'

You aren't supposed to memorize this fact about bromouracil. You are, however, expected to understand how the base pairing works so that if they give you a question like this on the MCAT you will be able to break down the question, write out the new DNA or RNA strands to get the answer.

Hope this helps,

Vanessa