Which of the Following Is True of Fixed-Proportions Production

Multiple Choice

Which of the following is true of fixed-proportions production?

A) The inputs used in production have constant marginal products.
B) An increase in the price of an input will lead the firm to substitute away from it.
C) The inputs used in production display diminishing marginal returns.
D) The inputs used in production are perfect complements.
E) The marginal cost of the inputs used in production is fixed.