Answer:
a. of the central limit theorem.
Explanation:
The Central Limit Theorem estabilishes that, for a random variable X, with mean
and standard deviation
, a large sample size, larger than 30, can be approximated to a normal distribution with mean
and standard deviation

In this problem, the sample size is 100, so it is sufficiently large to use the Central Limit Theorem. The mean of the sample in 69 and the standard deviation of the sample is 0.58.
So the correct answer is:
a. of the central limit theorem.