is it "who care" or "who cares"?

[Kwfine]

Is it "who care" or "who cares"?
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各位前輩安安, 我是kitty喔!

[Jamie (K)]

If you're simply asking a question, it has to be, "Who cares?" because "who" is third person singular in questions.

However, in an adjective clause, it would depend on who "who" refers to.

That is a person who cares about others.
They are people who care about others.