Evaluate the effect of NAFTA over the market for corn in the North American region (U.S., Canada, and Mexico). In 1994, before NAFTA rules binded, the demand for corn in the U.S. was Q = 1 P; Q = 1 2P in Canada; and Q = 1 3P in Mexico, respectively. Calculate the demand for corn in the North American trade region: (1 point) (a) QNA = 1 P (b) QNA = 2 3P (c) QNA = 3 3P (d) QNA = 3 6P