BUN used for kidney function tests stands for:

Correct option is C

BUN stands for blood urea nitrogen, a test that measures the amount of nitrogen in the blood that comes from urea, a waste product formed when the body breaks down proteins. Elevated levels can indicate kidney dysfunction or dehydration.
Explanation of options: (a) ✘ Blood uric acid nitrogen – Incorrect, refers to uric acid, not urea. (b) ✘ Blood uracil nitrogen – Uracil is a component of RNA, not related to BUN. (c) ✔ Blood urea nitrogen – Correct; used for assessing kidney function. (d) ✘ Blood urine nitrogen – Incorrect; urine is excreted, not measured in this test.