Expression A = (18500)(0.96)^3t, implying that at t = 1/3 years = 4 months, the exponent will be 1, meaning that the value will be multiplied by 0.96 (which is a decrease of 4%). This fits the third choice.
Expression B has a factor of (1.18)^t/3, implying that at t = 3 years, the exponent will be 1, meaning that the value is multiplied by 1.18, which is a growth of 18%. This also fits the third choice.