Price per unit 20 units production 40000 variable cost per unit 5

(C)75%

Sales   20*40000              =800,000

Variable cost5*40000      =200,000

Contribution Margin           =600,000 (600,000/800,000)%  =75% 

(C) is the Correct Ans.

Contribution = Sale  -  Variable Cost

                         =20   -  5

                         =15 / Unit  @40,000 Units =600,000

So, Contribution Margin is,

                   =600,000 /800,000*100

                   =    75% 

Sales - variable cost =15

Answer option:  75%