Let Q(t) denote the population of a certain country at time t. In 1970, the population was 2.4 million and increasing at a rate of 2.5% per year; in 1993, it was 4.6 million and increasing at 1.9% per year. In which year, 1970 or 1993, was dQ dt (the rate of growth of Q with respect to t) greater? Choose the correct year below. O A. 1993 O B. 1970 O C. Cannot be determined