Marginal Utility Curve: Falling

The marginal utility curve represents the relationship between the quantity of a good consumed and the additional utility or satisfaction derived from consuming one more unit of that good. It is important to note that the marginal utility curve is always downward sloping or falling. This means that as more units of a good are consumed, the additional utility or satisfaction obtained from each additional unit decreases.

Explanation:

1. Definition of Marginal Utility:
- Marginal utility refers to the additional utility or satisfaction obtained from consuming one more unit of a good.
- As more units of a good are consumed, the additional utility derived from each additional unit diminishes.

2. Law of Diminishing Marginal Utility:
- The marginal utility curve is based on the Law of Diminishing Marginal Utility.
- According to this law, as the quantity of a good consumed increases, the marginal utility derived from each additional unit decreases.
- This occurs because as more units of a good are consumed, the consumer's needs and wants for that good are gradually satisfied, leading to a decrease in the additional satisfaction gained from each additional unit.

3. Downward Sloping Marginal Utility Curve:
- The marginal utility curve is always downward sloping or falling due to the Law of Diminishing Marginal Utility.
- As more units of a good are consumed, the marginal utility derived from each additional unit decreases, resulting in a downward sloping curve.
- This implies that the initial units of a good provide a higher level of satisfaction compared to the later units.

4. Example:
- Let's consider the consumption of chocolate bars as an example.
- Initially, when a person consumes the first chocolate bar, it provides a high level of satisfaction or utility.
- However, as more chocolate bars are consumed, the additional utility derived from each additional bar decreases.
- For example, the second chocolate bar may provide slightly less satisfaction than the first, the third chocolate bar may provide even less satisfaction, and so on.
- This diminishing additional satisfaction is represented by the downward sloping marginal utility curve.

In conclusion, the correct answer is option 'D': falling. The marginal utility curve is always downward sloping or falling due to the Law of Diminishing Marginal Utility. As more units of a good are consumed, the additional utility or satisfaction derived from consuming each additional unit decreases.