Producing one yard of cloth requires 3 worker and 1 capital, while producing one pound of food requires 1 worker and 2 capital. Both countries have 720 workers; the United States has 480 capital, while ROW has 720. The price of food is always $24/pound; the price of cloth is $22/yard in the United States in autarky and $32/yard in both countries under free trade. The labor constraint is

a. QC + 2QF = 720
b. QC + 3QF = 720
c. 2QC + QF = 720
d. 3QC + QF = 720
e. none of the above