If an economy with full employment operating on its production possibilities curve can increase its output of steel from 0 to 30 tonnes by forgoing an output of 30 tonnes of soybeans output, then the opportunity-cost ratio (domestic exchange ratio) for the two products is Blank______.
A) 2 tonnes of steel for 1 tonne of soybeans or 2St = 1Soy
B) 1 tonne of steel for 1/2 tonne of soybeans or 2St = 1Soy
C) 1 tonne of steel for 1 tonne of soybeans or 1St = 1Soy
D) 1 tonne of steel for 2 tonne of soybeans or 1St = 2Soy