The Optimal Combination of Goods for a Consumer to Purchase

The optimal combination of goods for a consumer to purchase is shown by

A) any intersection of the indifference curve and the budget line.
B) the point where the budget line touches the vertical axis.
C) a point of tangency between the budget line and the indifference curve.
D) the point at which the indifference curve parallels the horizontal axis.
E) the intersection of two indifference curves.