Which description of the parts of the compound interest expression is correct? P(1 + )nt P = principal; r = number of times interest is compounded per year; n = annual interest rate; t = time in years P = principal; r = annual interest rate; n = number of times interest is compounded per year; t = time in number of compounding periods P = principal; r = monthly interest rate; n = number of times interest is compounded per year; t = time in number of compounding periods P = principal; r = annual interest rate; n = number of times interest is compounded per year; t = time in years