Answer:
D. measures the degree to which one input can be substituted for another, output held constant.
Step-by-step explanation:
Marginal Rate of Technical Substitution is the rate at which producer gives up one input, in exchange of other input, maintaining the same output level.
So implicatively, it denotes the degree to which one input can be substituted for another, output held constant.
MRTS (K,L) = MP L / MP K = w / r ; Where :-
K = Capital, L = Labour, MP L = Marginal Productivity of Labour, MP K = Marginal Productivity of Capital, w = Wages, r = Rent
MRTS is diminishing, because of decreasing marginal productivities of factor inputs.