Answer:
b. It is used to construct confidence intervals for the population mean when the population standard deviation is known
Explanation:
Student's t-distribution, also called sometimes just as t distribution, is a probability distribution that is used to estimate population parameters when you have small sample size, specifically when sample size is less than 30, or when the population standard deviation is unknown.
The t distribution allows us to conduct statistical analyses on samples that does not satisfy the conditions for applying standard normal distribution.