Biology

Answer: C

Explanation:

Correct option: During pregnancy, the kidneys increase in size due to hormonal changes and increased blood volume.
Hormones like progesterone cause the smooth muscles in the urinary tract to relax, which can lead to dilation of the ureters.
The glomerular filtration rate also increases, and the kidneys have to handle the increased metabolic waste from both the mother and the fetus.
So, option C is correct.

Incorrect options:

Option A: The kidneys ...