Supply Shift Right in 2011, Demand Shift Left in 2015

Steps:

• Increased production in 2011 shifts supply curve right, lowering price and raising quantity to new equilibrium Q from initial X.
• Decreased demand in 2015 shifts demand curve left, further lowering price and reducing quantity to equilibrium R from Q.
• Diagram shows X at intersection of original supply and demand, Q at new supply with original demand, R at new supply with new demand.
• Both events cause price falls, matching observed data.

Why A is correct:

• A matches law of supply/demand: rightward supply shift increases equilibrium quantity (to Q), leftward demand shift decreases it (to R), both reducing price.

Why the others are wrong:

• B: Incorrectly places 2011 at S, which likely shows demand shift, not supply increase.
• C: Wrongly assigns 2011 to T (possibly double shift) and 2015 to S (ignores demand decrease effect on quantity).

Final answer: A