Final answer:
Option 3, with a new demand curve P = 400 - 2Qd and supply curve P = 200 + 2Qs, best represents the market for LCD TVs after new manufacturers start selling LED TVs. The leftward shift in demand indicates a lower quantity demanded at each price level.
Step-by-step explanation:
When new TV manufacturers start selling LED TVs, which are of better quality than LCD TVs, the demand for LCD TVs is likely to decrease because consumers will prefer the newer technology. This would result in a shift to the left of the demand curve for LCD TVs, meaning that the quantity demanded at each price level would be lower.
Of the given options, option 3 describes this situation best: P = 400 - 2Qd, P = 200 + 2Qs. Here the new demand curve has a lower vertical intercept, reflecting a decrease in the maximum price consumers are willing to pay for the same quantity of LCD TVs.
The supply curve remains unchanged because the question does not indicate that the cost of producing LCD TVs or the quantity supplied at each price level has changed as a result of new manufacturers entering the market.