The reward for capital is interest. Capital refers to the money or assets that are used to invest in a business or enterprise. When someone invests their capital into a business, they expect to earn a return on their investment. The return on investment for capital is called interest. Interest is the amount of money paid by the borrower to the lender for the use of their capital. This can be in the form of regular interest payments or a lump sum at the end of the investment period. The interest rate is determined by various factors such as market conditions, inflation, and risk. Therefore, interest is the primary reward for capital.