Priority is the ones vs priority are the ones?

A - Top priority are the ones you already know.

B - Top priority is the ones you already know.

C - Top priorities are the ones you already know.

Is A correct or B?

I'm inclined towards A.

I think C is correct.

A and B are both incorrect because they mix tenses.

Top priority (singular) are the ones (plural) you already know.

Top priority is (singular) the ones (plural) you already know.

C is almost correct, but you are missing the word "the":

The top priorities are the ones you already know.