Suppose We Measure the Quantity of Good X on the Horizontal

Multiple Choice

Suppose we measure the quantity of good X on the horizontal axis and the quantity of good Y on the vertical axis. If indifference curves are bowed inward, as we move from having an abundance of good X to having an abundance of good Y, the marginal rate of substitution of good Y for good X (the slope of the indifference curve)

A) rises.
B) stays the same.
C) could rise or fall depending on the relative prices of the two goods.
D) falls.