Which of the following is a correct definition for one of the variables fundamental to all compound interest problems?

A. The number of time periods is the number of compounding periods where each period may be equal to or greater than a year.

B. The future value is the value at a future date of a given sum or sums invested assuming simple interest.

C. The rate of interest is a semi-annual rate that must be adjusted, if necessary, to the length of the compounding period.

D. The present value is the value now (present time) for a future sum or sums discounted assuming compound interest.