A salesman sells two types of trousers: cotton and woollen. A pair of cotton trousers is sold at 30% profit and pair of woollen trousers is sold at 50% profit. The salesman has computed that if he sells 100% more woollen trousers than cotton trousers, his entire profit will be 45%. But he ends up selling 50% more cotton trousers than woollen trousers. What will be his entire profit?
A. 37.5%
B. 40%
C. 41%
D. 42.33%