Which of the Following Will Lead to an Upward Shift

Two inputs,labor and capital,are considered complements if: A)a fall in the price of labor leads to a fall in the price of capital. B)they can replace each other in the production process. C)a fall in the price of labor leads to an increase in the price of capital. D)increasing the quantity of labor increases the marginal product of capital.

Two inputs,labor and capital,are considered substitutes if: A)a fall in the price of labor leads to no change in the price of capital B)the marginal rate of technical substitution of labor for capital is less than one. C)a fall in the price of labor leads to an increase in the price of capital D)increasing the quantity of labor decreases the marginal product of capital