The t distribution should be used whenever . Group of answer choices the sample size is less than 30 the population is not normally distributed the sample standard deviation is used to estimate the population standard deviation None of the answers is correct.

A: the sample size is less than 30

Step-by-step explanation:

Usually, the t-distribution is used instead of normal distribution in calculation of the mean of a normally distributed population when the sample size is small (n < 30) and if the population standard deviation is not known.

Thus, looking at the options, the correct one is Option A.