The price of X was $10 in year 1 and $14 in year 2. Which of the following could be the correct reason for the rise in price? a. The demand for X was higher in year 2 than in year 1, ceteris paribus. b. The supply of X was lower in year 2 than in year 1, ceteris paribus. c. The demand was higher, and the supply was lower, in year 2 than in year 1. d. a and b e. a, b, and c