Market Supply Curve Definition Steps:

• Recall that a supply curve graphs quantity supplied versus price, holding other factors constant (ceteris paribus).
• Examine option A: Income levels relate to demand, not supply.
• Examine option B: Factor levels (e.g., inputs) shift supply but don't define the curve itself.
• Examine option C: It matches the standard definition, varying price with technology fixed.
• Examine option D: Time changes can shift supply but aren't the curve's basis.

Why C is correct:

• By the law of supply, the curve shows increasing quantity supplied as price rises, assuming technology and other factors unchanged.

Why the others are wrong:

• A: Income affects demand curves, not supply.
• B: Factor changes shift the entire supply curve, not plot points on it.
• D: Time variations cause supply shifts, not the price-quantity relationship.

Final answer: C