Hello! So the formula for compound interest is P(1 + r)^t, where r = rate, P = principal, and t = time (years). C is out, because you multiply the rate and principal together to get the price, not add. You raise the decimal to a certain power, based on the amount of years. You add 1 to the rate. 5% in decimal form is 0.05 and you must add 1 to the amount, which eliminated B. The only answer that works is A, because it shows the correct formula. The answer is A.
