Within a general equilibrium setting, which of the following is NOT necessarily true?

a) at the point where indifference curves intersect, the marginal rates of substitution for the two consumers are equal

b) consumers' indifference curves will be tangential along the entire length of the contract curve.

c) pareto optimal points will mean that all mutually beneficial gains from trade have been exhausted

d) intersecting indifference curves will indicate a pareto inefficient allocation