A. The local police asked the F.B.I. to assist with the case.
-F.B.I isn't properly punctuated, as there's a period after 'F.B.I', which implies the sentence ends there.
B. Mary remembered to buy milk didn't she?
-Should be 'Mary remember to buy milk, didn't she?'
C. Mr. Jones visited the YMCA before becoming a member.
-This is correct
D. The company held it's annual party at the convention center.
-It's isnt proper, It's is basically 'it is', The company held it is annual party at the convention center obviously does not make sense.
