Refer to the revenue and cost schedule for Shelly Shoes in addressing the question below. Quantity Price Total Marginal Total Cost Marginal Average Revenue Revenue Cost Cost $37 $240 10 $31 $310 20 $26 $390 30 $22 $530 35 $20 $690 40 $19 $900 When increasing production from 0 to 10 dress shoes, the marginal revenue is $_ _ and marginal cost is $ O a) 28; 9 O b) 31; 7 O c ) 26; 8 O d) 33; 11