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: Smaller tributary glaciers, like tributary streams, flow into the main glacier in their own shallower U-shaped valleys.
Question: What would happen to the size of the valley created by a tributary stream if the size of the stream were to be increased?
Choices: A)the valley would be shallower
B)the valley would be deeper
the valley would be deeper