How does a change in the price of one input change the firm's long-run expansion path? if the price of an input changes, then the a. slope of the isocost lines will change, and the firm will substitute away from the relatively more expensive input, pivoting the expansion path toward the axis of the relatively cheaper input. b. isoquants will shift in a parallel fashion, and the firm will substitute away from the relatively more expensive input, pivoting the expansion path toward the axis of the relatively more expensive input. c. isocost lines will shift in a parallel fashion, and the firm will substitute away from both inputs, shifting the expansion path in a parallel fashion. d. slope of the isoquants will change, and the firm will substitute toward the relatively cheaper input, pivoting the expansion path toward the axis of the relatively cheaper input.