A company makes different coloured pens but has a limited supply of materials. Using the data below, in what order of priority should the pens be made: Blue Black Red Sales price 17.50 21.50 23.75 tion Material cost per 6.40 7.20 10.50 pen Labour cost per 3.00 3.00 3.00 pen O a. Black, blue, red O b. Red, black, blue O c. Blue, black, red O d. Black, red, blue.