Which of the following statements is true?

A. The share of bank operating income earned from off-balance-sheet activities has increased over the past two decades.

B. To keep enough cash on hand to meet depositors' demand for withdrawals, banks must engage in trading.

C. Since a bank's assets exceed its equity capital, the return on assets always exceeds the return on equity.

D. If a bank has ample excess reserves, a deposit outflow necessitates changes from other parts of its balance sheet.

E. If a bank does not have excess reserves, a deposit outflow necessitates decreasing loan loss reserves.