Question

David's indifference curves are flatter than Alison's indifference curves. They have the same amount of income and pay the same prices for the two goods X and Y, and their optimal bundles are interior solutions. If Y is measured on the vertical axis, at their optimal bundles:
A. David's marginal rate of substitution is higher than Alison's marginal rate of substitution.
B. Alison's marginal rate of substitution is higher than David's marginal rate of substitution.
C. David and Alison have the same marginal rate of substitution.
D. David's optimal bundle contains less of good Y than Alison's optimal bundle.