According to the law of demand in economics, an increase in the price of a good will generally lead to which of the following outcomes?

Introduction / Context:
This question tests a fundamental concept in microeconomics: the law of demand. The law of demand describes how the quantity demanded of a good changes when its price changes, holding other factors constant. It is essential to distinguish between a change in demand, which shifts the entire demand curve, and a change in quantity demanded, which is a movement along a given demand curve. Correctly applying this distinction is crucial in answering many pricing and market behaviour questions.

Given Data / Assumptions:
- The scenario involves an increase in the price of a good.
- Other determinants of demand, such as income and tastes, are assumed to remain constant (ceteris paribus).
- The options mix up changes in quantity demanded with changes in demand (curve shifts), as well as directions of change.
- We assume a normal downward sloping demand curve.

Concept / Approach:
The law of demand states that, other things being equal, when the price of a good rises, the quantity demanded falls, and when the price falls, the quantity demanded rises. This relationship is represented by a movement along the demand curve. A shift of the entire demand curve occurs only when a non price determinant changes, such as income, preferences or the prices of related goods. Therefore, an increase in price should produce a decrease in quantity demanded along a given demand curve, not a shift of the curve itself.

Step-by-Step Solution:
Step 1: Identify that the only change mentioned is in the price of the good. Step 2: Recall that a price change causes movement along the demand curve, altering the quantity demanded but not the position of the curve. Step 3: Apply the law of demand: an increase in price leads to a lower quantity demanded. Step 4: Select the option that states "decrease quantity demanded of the good along a given demand curve". This matches both the direction of change and the concept of movement along the curve.

Verification / Alternative check:
You can verify this by visualising a typical demand graph with price on the vertical axis and quantity on the horizontal axis. The curve slopes downward. Starting from one point on the curve, if price increases, you move up along the curve, which corresponds to a lower quantity on the horizontal axis. The curve itself does not shift left or right unless something other than price, such as consumer income, changes. This simple mental picture confirms that the correct effect is a decrease in quantity demanded along the existing demand curve.

Why Other Options Are Wrong:
Option A states that demand decreases and the demand curve shifts leftward. A shift in demand requires a change in non price factors, not a price change alone, so this statement is incorrect in the given context.
Option B claims that quantity demanded increases when price rises, which contradicts the basic law of demand for normal goods.
Option C suggests that demand increases and the demand curve shifts rightward after a price increase, which is opposite to typical behaviour and again confuses movement along the curve with a shift of the curve.

Common Pitfalls:
A common mistake is to confuse the terms "demand" and "quantity demanded", using them interchangeably. Many students incorrectly say "demand decreases" when they mean that quantity demanded falls due to a higher price. Another pitfall is to assume that every change in market conditions shifts curves instead of causing movement along them. To avoid these problems, remember that only non price determinants shift demand; price changes cause movement along the existing demand curve.

Final Answer:
According to the law of demand, an increase in the price of a good will decrease quantity demanded of the good along a given demand curve.