by reading the formula of the standard errors we know that a

by reading the formula of the standard errors we know that as the number of cases increases (N) the standard error of the sampling distrubtion for the difference between means becomes:

a. more normal b. smaller c. larger d. closer to the mean e. closer to the population standard deviation

Solution

standard error = standard deviation / sqrt(N)
as the number of cases increases (N) the standard error of the sampling distrubtion for the difference between means becomes
b. smaller