Market Structures Where Advertisement is Common

Advertisement is a key strategy used by firms primarily in markets where they can differentiate their products and face competition. Let's analyze the given market structures:

• Oligopoly: In an oligopoly, a few firms dominate the market. These firms are interdependent, and advertisement is commonly used to gain market share, build brand loyalty, and influence competitors.
• Perfect Competition: This market structure features numerous firms selling identical products. Since products are identical and firms are price takers, there is no incentive for individual firms to advertise.
• Monopolistic Competition: Characterized by many firms selling differentiated products, this market heavily relies on advertisement. Firms use advertising to highlight their unique features, attract customers, and stand out from competitors.
• Monopoly: A single firm controls the entire market. While a monopolist might advertise to influence demand or improve its image, it's not a defining or common feature driven by competitive pressures like in oligopoly or monopolistic competition.

Based on this analysis, advertisement is common in Oligopoly (i) and Monopolistic Competition (iii).

Correct Option Identification

The market structures where advertisement is common are Oligopoly and Monopolistic Competition. This corresponds to options (i) and (iii).

Therefore, the correct choice is the one that includes both (i) and (iii).