For each of the following kinds of wage payments, indicate whether or not the wages are exempt from the withholding of federal income taxes:
a. Three weeks' vacation pay.
b. Weekly advance to a sales representative for traveling expenses to be incurred.
c. Weekly wages paid the housekeeper in a college fraternity.
d. Monthly salary received by Rev. Cole Carpenter.
e. Payments under a worker's compensation law for sickness or injury.