Which one of the following questions is true? a. Arithmetical mean of a sample with bounded 1st and 2nd moment is a consistent estimator of the expected value. O b. Cramer-Rao lower bound can be applied to an unbiased estimator of ) if a sample is distributed according to gamma distribution Gamma(r, A). c. Transformation of any sufficent statistics is a sufficient statistics itself. O d. Any estimator based on method of moments is always biased. O e. Any maximum likelihood estimator is sufficient. Of. Cramer-Rao lower bound can be applied to any estimator of theta if a sample is distributed according to fe(x) = e-x/0/0, x 2 0. Ig. Given a sample of normally distributed random variables, the average over the sample is an estimator of mean, that is a) unbiased, b) the most efficient among unbiased estimators of mean, c) sufficient, d) consistent Oh. Variance of any maximum likelihood estimator attains the Cramer-Rao lower bound