In microeconomics, the change in quantity supplied that occurs due to a change in the price of a good, while other factors remain constant, is described as what movement along the supply curve?

Introduction / Context:
In the theory of supply, it is important to distinguish between movements along a given supply curve and shifts of the entire supply curve. The question focuses on what we call the change in quantity supplied that happens purely because the price of the good changes, assuming that all other determinants of supply remain unchanged. This is a standard terminology check in introductory microeconomics.

Given Data / Assumptions:

• There is a given supply curve for a particular good.
• Only the price of the good is changing.
• All other supply determinants (technology, input prices, number of firms, taxes, expectations) are constant.
• We are interested in the name for movement along the existing curve.

Concept / Approach:
When price changes and supply conditions aside from price remain unchanged, we move along the same supply curve. An increase in price leads to a higher quantity supplied, called expansion of supply. A decrease in price leads to a lower quantity supplied, called contraction of supply. Together, these movements are summarized as expansion and contraction of supply. By contrast, changes in other factors cause the entire curve to shift to the right or left and are described as increase or decrease in supply, not expansion or contraction.

Step-by-Step Solution:
Step 1: Recognize the phrase “movement along the supply curve” as a key hint. Step 2: Recall that a movement along the curve is due solely to price changes. Step 3: Remember that higher price leads to expansion of supply and lower price leads to contraction of supply. Step 4: Conclude that movement along the supply curve is collectively described as “expansion and contraction of supply”.

Verification / Alternative check:
A quick check is to contrast this with the phrase “increase in supply”. An increase in supply refers to a rightward shift of the entire supply curve because of improved technology or lower input costs, not just a change in price. Since the question explicitly mentions movement along the supply curve, the only correct technical expression is expansion and contraction of supply.

Why Other Options Are Wrong:
Increase in supply: This means a shift of the entire supply curve to the right, due to non price factors, not movement along the curve.
Contraction of supply only: This refers only to the case when price falls and quantity supplied falls, so it is incomplete because it ignores expansion of supply.
Expansion of supply only: This refers only to the case when price rises, so it again ignores contraction of supply and is incomplete.

Common Pitfalls:
Learners often confuse the phrases increase in supply and expansion of supply, as well as decrease in supply and contraction of supply. Remember that expansion and contraction are associated with movements along the same curve due to price changes, while increase and decrease refer to shifts of the curve due to other determinants. Understanding this distinction is crucial for interpreting diagrams and exam questions correctly.

Final Answer:
Movement along the supply curve due to changes in price is known as expansion and contraction of supply.