A dividend reinvestment plan (DRIP) is a(n):

a. Optional investment plan, provided by brokerage firms, allowing shareholders to automatically reinvest dividend payments in additional shares of the firm's stock.

b. Optional investment plan, provided by large corporate firms, allowing shareholders to automatically reinvest dividend payments in additional shares of the firm's stock.

c. Mandatory investment plan, provided by brokerage firms, in which shareholders are automatically reinvesting dividend payments in additional shares of the firm's stock at a reduced price.

d. Mandatory investment plan, provided by large corporate firms, in which shareholders automatically reinvest dividends into additional shares of the firm's stock at a reduced price.