Alford, Brooks, and Fitch Companies Below Are Income Statements That

Alford, Brooks, and Fitch Companies Below are income statements that apply to three companies: Alford, Brooks, and Fitch:
Refer to Alford, Brooks, and Fitch Companies. Within the relevant range, if sales go up by one unit for each firm, which firm will experience the greatest increase in net income?

A) Alpha Company
B) Beta Company
C) Fitch Company
D) can't be determined from the information given