Which of the following statements about employee discount is correct?
a. Discounts can't be provided on commission charged by a brokerage house or insurance company.
b. In order to avoid the receipt of taxable income, the discount must be for the purchase of investment assets, such as real estate or securities.
c. The amount of the discount is not includible in an employee's gross income, even if the discount is provided only to highly compensated employees.
d. Discounts on merchandise can't exceed the gross profit percentage at which it is sold to customers.