At one point along a PPF, 40 tons of wheat are produced while 80 tons of rice are produced. At another point along the same PPF, 41 tons of wheat are produced while 70 tons of rice are produced. The opportunity cost of producing a ton of wheat between these points is ________ per ton of wheat.
A) 10 tons of rice
B) 1 ton of rice
C) 10 tons of wheat
D) 1 ton of wheat
