Assume the contribution margin per unit (CMU) of a certain product is greater than zero. Which of the following would produce the largest increase and why? A) 10% increase in Selling price? B) 10% decrease in variable cost? C) 10% decrease in fixed cost? D) 10% increase in number of units sold? E) (More than one above is correct)? Solution Answer is A) 10% increase in Selling price It is due to the fact that an increase in selling price without any increase in variable cost does raise the contribution and hence, results in largest increase in Contribution margin Per Unit..