TRUE or FALSE (Determine if each of the following statements is true or false. Explain your reasoning.)
(a) Assume the prices of all goods are positive. The Engel curve of each good must pass through the origin.
(b) If a good is an inferior good, then the substitution effect and the income effect are of opposite signs.
(c) If the consumer has Cobb-Douglas preferences, it is impossible for one of the goods to be a Giffen good.
(d) If a consumer has quasilinear preferences over two goods, then her consumption of neither good depends on her level of income.