Indifference Curve Convexity and Slope

Indifference curves are generally depicted as convex to the origin. This shape reflects the concept of the Diminishing Marginal Rate of Substitution (MRS).

The slope of an indifference curve represents the MRS. The MRS indicates how much of one good (e.g., good Y) a consumer is willing to sacrifice for one additional unit of another good (e.g., good X), while remaining equally satisfied.

Consider movement along a standard indifference curve:

• Moving down and to the right signifies consuming more of good X and less of good Y.
• To get an additional unit of X, the consumer is willing to give up progressively less of good Y.
• This means the absolute value of the negative slope $| \frac{dY}{dX} |$ decreases.
• Consequently, the algebraic value of the slope, which is negative, increases (becomes less negative, e.g., moving from -3 to -2).

Therefore, the property of convexity implies that the slope of the indifference curve increases as the consumer moves down along the curve.

The correct option is B.