Which of the Following Statements Are Correct

Which of the following statements are correct?

A) If there are two unbiased estimators of a parameter, the one whose variance is larger is said to be relatively efficient.
B) If there are two unbiased estimators of a parameter, the one whose mean is larger is said to be relatively efficient.
C) If there are two unbiased estimators of a parameter, the one whose mean is smaller is said to be relatively efficient.
D) If there are two unbiased estimators of a parameter, the one whose variance is smaller is said to be relatively efficient.