The correct answer is letter A.
Explanation: Interest is the income you earn when you lend money for a specified period. Interest is to the lender (the one who has something to receive) compensation for the time it captures without using the borrowed money.
To determine the amount of interest, percentage rates (interest rates) are set by the lender.
Interest rates are calculated according to some factors such as the prevailing inflation, what was agreed in the contract or the risk of the loan to the lender.