Which of the following is false?
1) A change in input prices shifts the isoquant map.
2) Convex isoquants mean that the marginal rate of technical substitution decreases as the firm substitutes labor for capital.
3) A change in cost shifts the isocost curve.
4) At the optimal input choice, the rate at which the firm can substitute labor for capital in production is equal to the rate at which the firm can substitute labor for capital in the market.
5) None of the above.