Final answer:
A firm facing a horizontal demand curve operates in perfect competition and is unlikely to price its goods above market price, because doing so would result in losing sales to competitors.
Step-by-step explanation:
A firm facing a horizontal demand curve can be best described by option (c): it is unlikely to price its goods above market price. Such a firm operates in a market structure known as perfect competition, where many firms sell an identical product, and no single firm has any influence over the market price. Because there are many substitutes available, if the firm raises its price above the market level, customers would switch to competitors, and the firm would lose sales. Conversely, lowering the price below the market level would not be beneficial either since the firm can sell all it wants at the market price. Therefore, a perfectly competitive firm has no incentive to change the price it charges.