Answer: A. the firm could produce 3 more units of output if it increased its use of capital by one unit (holding labor constant).
Step-by-step explanation:
The Marginal Rate of Technical Substitution(MRTS) is calculated as follows:
= Marginal product of labor / Marginal product of capital
= 1 / 3
Marginal product of labor = 1
Marginal product of capital = 3
This means that if one unit of labor is used, it produces 1 unit of output.
If one unit of capital is used however, it produces 3 units of output.
If a firm therefore used one unit of capital and kept labor constant, it could produce 3 units out output.