Explanation:

- Perfect Competition (Option 1)

- A firm is a price-taker in this market.

- Many sellers and buyers exist.

- Products are homogeneous.

- No individual firm can influence market price.

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- Monopoly (Option 2)

- Single seller dominates the market.

- No close substitutes for its product.

- Firm has significant control over pricing.

- Monopolistic Competition (Option 3)

- Many sellers with differentiated products.

- Some pricing power due to differentiation.

- Firms compete on factors other than price.

- Oligopoly (Option 4)

- Few dominant firms in the market.

- Firms may collude to set prices.

- Pricing influenced by competitors' actions.