In​ 2018, two members of Congress introduced the Stop Bad Employers by Zeroing Out Subsidies​ Act, which would tax firms whose employees receive government assistance. These members of Congress thought this legislation would give firms a reason to raise employee wages so fewer employees would receive the government assistance. These members of Congress were counting on firms reacting to which key economic​ idea?

A. The market system relies on the principle of voluntary exchange.
B. Optimal decisions are made at the margin.
C. People respond to economic incentives.
D. People are allocatively efficient.