Which of the Following Would Lead to an Increase in a Commercial

Which of the following would lead to an increase in a commercial bank's reserve account?

A) An increase in the number of bad checks written by the bank's customers.
B) An increase in cash on hand in the bank to meet seasonal demands by its customers.
C) An increase in the number of, and balances in, demand deposit accounts at the bank as a result of a promotional program.
D) All of the above.