The sales of a new high-tech item (in thousands) are given by the following function, where t represents time in years. Find the rate of change of sales at each time. S(t) = 100-90e-0.4t (a) After 1 year. (b) After 5 years. (c) What is happening to the rate of change of sales as time goes on? (d) Does the rate of change of sales ever equal zero? . . . (a) The rate of change after 1 year is |thousand items per year. (Round to three decimal places as needed.) (b) The rate of change after 5 years is thousand items per year. (Round to three decimal places as needed.) (c) What is happening to the rate of change of sales as time goes on? O A. First it increases, then it decreases. O B. It always decreases. O C. It always increases. O D. First it decreases, then it increases. (d) Does the rate of change of sales ever equal zero? Yes No