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: Aerobic exercise increases the size and strength of muscles in the heart and helps all your muscles develop greater endurance.
 Question: If one does no aerobic exercises, their heart muscles will become 
 Choices: A)stronger 
B)weaker
weaker