What does it mean when US immigration stamps C on your passport ?

Question

I was told it means Caucasian (White) hoe possibly racially prejudiced are they then. I can't be bothered about being white but I do wonder about people who take note of it.

Answer 1

You are class C, AB is the best

Answer 2

You are the team Captain.

Answer 3

you need more vitamin C

Answer 4

probably cleared