Ford Assembles Some Cars in Mexico Because the Lower Wages

Ford assembles some cars in Mexico because the lower wages the company pays to Mexican workers and the lower prices it pays for auto parts in Mexico reduces Ford's costs.This is an example of Ford reacting to which of the three key economic ideas?

A) People are rational.
B) People respond to economic incentives.
C) Optimal decisions are made at the margin.
D) Firms attempt to maximize revenues.