Each of a company's several product lines has a different contribution margin ratio. Total sales in 2021 were 15% higher than total sales in 2020. Total contribution margin for 2021 will be:

A. more than 15% higher than it was in 2010, if the sales mix changes and proportionately more high contribution margin ratio products are sold in 2011 than in 2010.

B. less than 15% higher than it was in 2010, if the sales mix changes and proportionately more high contribution margin ratio products are sold in 2011 than in 2010.

C. the same as it was in 2020, regardless of changes in sales mix.

D. 15% higher than it was in 2020, regardless of changes in sales mix.