in general, unbiased estimators are preferred for inference because:

a) unbiased estimators always have the least amount of variance of all possible estimators

b) bias in inference is always bad and should be avoided at all costs, so using unbiased estimators is the only way to conduct objective inference

c) in many cases the most probable value of an unbiased estimator is the value of the parameter being estimated; thus, unbiased estimators typically converge on values near the parameter

d) a biased estimator will almost always give very little insight into the parameter being estimated and, therefore, serve as a poor guess of the parameter's value