How Is the Unbiasness of Estimators Defined

Multiple Choice

How is the unbiasness of estimators defined?

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