Which of the following statements is (are) true concerning the time value of a single amount of money? (S1) The higher the discount rate, the higher the present value; (S2) The longer the time period, the higher the future value; (S3) The larger the amount, the larger the present value; (S4) The higher the discount rate, the higher the future value. S4 only S1 and S4 only S3 and S4 only S2, S3 and S4 only S1, S2 and S3 only