If a consumer is choosing the optimal combinations of two goods X and Y, and then the price of good Y decreases, this causes:
a. MU/P of good Y to increase, so the consumer now must buy more Y to find a new optimal combination.
b. demand for good X to increase.
c. MU/P of good X to increase, so the consumer now must buy more X to find a new optimal combination.
d. MU/P of good Y to decrease, so the consumer now must buy more Y to find a new optimal combination.