Final answer:
A company with a new, easily substituted product with little current competition is best described by D. Monopolistic competition, where many firms sell similar but differentiated products.
Step-by-step explanation:
The type of market situation that best describes a company with a new product that is easily substituted and has little competition currently in the market is D. Monopolistic competition. This scenario fits the characteristics of monopolistic competition because it involves many firms selling similar, but not identical, products. In monopolistic competition, products can be differentiated by several factors, including characteristics of the good or service, the location from which it is sold, and the perceptions of the product. Although the product is new and has little competition now, its easy substitutability indicates a market with differentiated products where new competitors can enter over time.