If marginal rate of substitution $$\left( {\frac{{\vartriangle {{\text{y}}_1}}}{{\vartriangle {{\text{y}}_2}}}{\text{or}}\frac{{\vartriangle {{\text{y}}_2}}}{{\vartriangle {{\text{y}}_1}}}} \right)$$   is equal to zero, then enterprise relation is said to be

A. Competitive

B. Supplementary

C. Complementary

D. None of these

Answer: Option C