If Two Goods Are Both Desirable and Preferences Are Convex

Multiple Choice

If two goods are both desirable and preferences are convex, then

A) there must be a kink in the indifference curves.
B) indifference curves must be straight lines.
C) if two bundles are indifferent, then an average of the two bundles is worse than either one.
D) the marginal rate of substitution is constant along indifference curves.
E) None of the above.