Let S(x) represent the total sales (in thousands of dollars) for the month x in the year 2005 at a certain department store. Represent each statement to the right by an equation involving S or S'. (a) The sales at the end of July reached $136,020 and were rising at the rate of $1700 per month. (b) At the end of December, the sales for this month dropped to $60,000 and were falling by about $6 day. (Use 1 month = 30 days.) (a) Choose the option with equations that best represent (a) above. OA. S(7) 136.020, S'(7)=-1.7 OC. S(7) 1.7, S'(7)=136.020 OB. S(7)=1.7, S'(7) = - 136.020 OD. S(7)=136.020, S'(7) = 1.7