The net profit of Carbon Footwear is $10 million. Its net marketing contribution is derived from sales of $80 million and the marketing and sales expenses amount to $15 million. The general and administrative expenses and other operating expenses amount to $20 million.

What is the total amount of Carbon Footwear's net marketing contribution? A) $10 million B) $20 million

C) $30 million

D) $40 million

E) $50 million