Which of the Following Is True About Stock Transactions and Fees

Which of the following is true about stock transactions and fees?

A) When purchasing stock, the cost of the brokerage fees should be subtracted.
B) When selling stock, the cost of the brokerage fees should be added.
C) Online fees and full service fees are usually a percent of the transaction.
D) Online fees are often flat fees and full service brokerage fees a percent of the transaction.