Explanation:

- Option 1: Upward sloping

- This option is typically incorrect for a demand curve. An upward sloping curve would suggest that as price increases, quantity demanded increases, which contradicts the law of demand.

- Option 2: Downward sloping

- Correct Answer: The demand curve for a monopoly is downward sloping. This means as the price decreases, the quantity demanded increases. Unlike in perfect competition, a monopoly has market power and can influence prices.

- Option 3: Horizontal

- This represents a perfectly elastic demand curve, usually seen in perfect competition. A monopoly doesn’t have a horizontal demand curve because it can set its own prices.

- Option 4: Vertical

- A vertical demand curve suggests perfectly inelastic demand, where quantity demanded doesn't change with price. This is not typical for monopolies.