How Is the Efficiency of Estimators Defined

Multiple Choice

How is the efficiency of estimators defined?

A) An estimator is efficient if its expected value equals the estimated population parameter.
B) An efficient estimator approaches the estimated population parameter as the sample size grows larger.
C) An estimator is efficient if it always gives the correct value of the estimated population parameter.
D) An unbiased estimator is efficient if its standard error is lower than that of other estimators of the estimated population parameter.