". This is because the sentence is discussing the details of an investment. An investor is the person who is putting money into an investment. The question then asks about whether the interest should be calculated in a specific way. "Cumulative" interest means that the interest earned also earns interest. This is a common feature of investments, and therefore it is the most logical choice to fit in the blank spaces and complete the statement. The sentence would read: "The investor can also decide whether the interest should be cumulative or annual."