A newborn baby has extremely low birth weight

(ELBW) if it weighs less than 1000 grams. A study of the health of such children in later years examined a random sample of 219 children. Their mean weight at birth was x– = 810 grams. This sample mean is an unbiased estimator of the mean weight m in the population of all ELBW babies, which means that

(a) in all possible samples of size 219 from this population, the mean of the values of x– will equal 810.

(b) in all possible samples of size 219 from this population, the mean of the values of x– will equal m.

(c) as we take larger and larger samples from this population, x– will get closer and closer to m.

(d) in all possible samples of size 219 from this population, the values of x– will have a distribution that is close to Normal.

(e) the person measuring the children’s weights does so without any error.