If all possible samples of size n are drawn from an infinite population with a mean of 15 and a standard deviation of 5, then the standard error of...

If all possible samples of size n are drawn from an infinite population with a mean of 15 and a standard deviation of 5, then the standard error of the sample mean equals 1.0 only for samples of size:

Select one:

a. 5.

b. 15.

c. 25.

d. 75.