Answer:
C. The original amount invested and previously paid interest payments
Explanation:
Compound interest is the interest calculations that take into account the principal amount and the interest payment summed up to calculate the subsequent interest payment. For example in year 0 there was an investment of 1000 and 10% interest payable annually,
Year 0 = 1000
Year 1 = 1000 + 100 (here hundred is the interest payment)
Year 2 = 1000 + 100 + 110 (110 is the compounded interest on 1000 +100 from previous periods)
Hope that helps.