Let S(t) = 18.5 + 3.5 sin be the sales function over 1 year where S is sales in thousands of dollars and t is time in months, with t = 1 corresponding to January. Which month has minimum sales? What is the minimum number of sales? a) O September; $22, 000 b) O June; $15, 000 c) O March; $22, 000 d) O March: $15, 000 e) O September; $15, 000 f) O None of the above