New Firms Increase Industry Supply Steps:

• Industry supply curve aggregates output from all firms at each price.
• Entry of new firms adds more producers to the market.
• Total quantity supplied rises at every price level.
• This causes the entire supply curve to shift rightward.

Why A is correct:

• New entrants boost total supply, increasing quantity at each price and shifting the curve right per the market supply definition.

Why the others are wrong:

• B: Left shift signals reduced supply, which occurs with firm exits, not entries.
• C: Downward movement along the curve results from a price drop, not structural changes like entry.
• D: Upward movement along the curve follows a price rise, unrelated to new firms.

Final answer: A