Which of the following statements is correct?
a. In a consumers’ utility maximization problems over current and future consumption goods, a higher rate of return r produces substitution and income effects that cause a decrease in quantity demanded of future consumption goods.
b. In a consumer’s utility maximization problems over current and future consumption goods, a higher rate of return (‘r’) produces substitution and income effects that cause an increase in quantity demanded of current consumption goods.
c. In a consumer’s utility maximization problem over current and future consumption goods, a higher rate of return (‘r’) produces substitution effects that that favor more saving and income effects that favor less.
d. All of the above.