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: Size restriction: The final body size is limited because as the body size increases, the surface area to volume ratio decreases.
 Question: As Jimbo grows older and his body size gets bigger, what happens to his surface area to volume ratio? 
 Choices: A)gets bigger 
B)gets smaller
gets smaller