Given the task definition and input, reply with output. You are given a short paragraph, a question and two choices to answer from. Choose the correct answer based on the paragraph and write the answer(not the key).

Paragraph: The pupil automatically gets bigger or smaller to let more or less light in as needed.
 Question: Sandra is in a dark building and then suddenly goes exits onto a sunny street. Sarah's pupils will do this in response to the new bright light 
 Choices: A)shrink 
B)grow
shrink