Correct Option: C Explanation: A rational consumer aims to maximize their total utility, which is the satisfaction or pleasure derived from consuming goods and services. To achieve this, they will adjust their spending pattern based on the concept of marginal utility, which is the additional satisfaction gained from consuming one more unit of a good or service. Step-by-Step Explanation:

1. Understanding Utility:
2. Total Utility (TU) is the overall satisfaction received from consuming a certain quantity of goods.
3. Marginal Utility (MU) is the additional satisfaction gained from consuming one more unit of a good.
4. The Principle of Equi-Marginal Utility:
5. A rational consumer will allocate their budget in such a way that the last naira spent on each good provides the same level of marginal utility. This is known as the Equi-Marginal Principle.
6. Mathematically, this can be expressed as: [ \frac{MU_A}{P_A} = \frac{MU_B}{P_B} = \frac{MU_C}{P_C} = \ldots ] where ( MU ) is the marginal utility and ( P ) is the price of the goods A, B, C, etc.
7. Why Option C is Correct:
8. Option C states that "the marginal utility he gets from the last naira spent on each item is the same." This aligns perfectly with the principle of maximizing utility. If a consumer spends their money such that the marginal utility per naira spent is equal across all goods, they are maximizing their total utility given their budget constraint.
9. Why Other Options are Incorrect:
10. Option A: "He buys only the one item that gives him most total satisfaction."
    • This option is incorrect because it suggests that the consumer would only purchase one item. In reality, consumers often derive satisfaction from a variety of goods. The goal is to balance the consumption of different goods to maximize overall satisfaction, not to focus on just one.
11. Option B: "The marginal utility he gets from the last unit of item is the same."
    • This option is misleading because it implies that the marginal utility from the last unit of each item must be equal. However, the consumer's goal is to equalize the marginal utility per naira spent, not the marginal utility itself. Different goods can have different marginal utilities, but the consumer will adjust their spending until the marginal utility per naira is equal.
12. Option D: "The total utility he gets from each item is the same."
    • This option is incorrect because total utility can vary significantly between different goods. Consumers do not aim to equalize total utility across items; rather, they seek to maximize total utility overall by balancing their consumption based on marginal utility.

Common Pitfalls:

• Confusing marginal utility with total utility. Remember, marginal utility refers to the additional satisfaction from one more unit, while total utility is the cumulative satisfaction from all units consumed.
• Misunderstanding the concept of utility maximization. It’s not about equal total utility or marginal utility across items, but rather about equalizing the marginal utility per unit of currency spent.

Revision Summary:

• A rational consumer maximizes total utility by equalizing the marginal utility per naira spent across all goods.
• The Equi-Marginal Principle is key to understanding consumer behavior in economics.
• Total utility can vary between goods, and consumers do not focus on just one item.
• Marginal utility is crucial for decision-making, not total utility or marginal utility of the last unit alone.