The incomes in a certain large population of electricians have a Normal distribution with mean $60,000 and standard deviation $8000. Four electricians are selected at random from this population to be shipped to another region.

A. The distribution of the mean, x-bar, is Normal with mean $30,000 and standard deviation $8000.
B. The distribution of the mean, x-bar, is Normal with mean $15,000 and standard deviation $8000
C. The distribution of the mean, x-bar, is Normal with mean $60,000 and standard deviation $2,000.
D. The distribution of the mean, x-bar, is Normal with mean $60,000 and standard deviation $4000.