Riya and Piya are partners in a firm. During the year 2009, Riya withdraw Rs. 1000 p.m. and Piya withdraw Rs. 500 p.m. on the first day of each month for personal use. Interest on drawing is to be charged @ 10% p.a. Total interest on drawings will be

(a) Rs. 975
(b) Rs. 650
(c) Rs. 900
(d) Rs. 325