Suppose that a consumer regards two types of soap as perfect substitutes for one another. The based on the prices and their utility, the consumer choose to only by the brand of soap on the X-axis. The price consumption path generated by lowering the price of the soap on the X-axis... Select one: a. is always upward sloping. b. is always horizontal. O c. is always vertical. O d. corresponds with the X-axis e. corresponds with the Y-axis