Explanation:

- TR stands for Total Revenue, which is Price × Quantity.

- If the price remains constant, and quantity increases, TR increases linearly—a straight line upwards, not horizontal.

- A horizontal TR line would mean Total Revenue doesn’t change regardless of quantity sold, which is only possible if price is zero or goods aren’t being sold—rare in real business scenarios.

- Thus, TR can’t be a horizontal line unless extremely unlikely economic conditions hold.

- Option 4: No is the correct answer.