FIGURE D.6 The Optimal Consumption BundleThe budget line, BL, shows Ingrid’s possible consumption bundles, given an income of $2,400 per month, when rooms cost $150 per month and restaurant meals cost $30 each. I1, I2, and I3 are indifference curves. Consumption bundles such as B and C are not optimal because Ingrid can move to a higher indifference curve. The optimal consumption bundle is A, where the budget line is just tangent to the highest possible indifference curve.