Final answer:
McDonald's and Burger King can decrease competition with a joint venture, a strategic alliance, or a merger, but forming a monopoly through collusion is illegal in many areas, including the U.S.
Step-by-step explanation:
When discussing the prospect of McDonald's and Burger King, two restaurants in competition in New York City, exploring ways to decrease competition and improve profitability, several business strategies come into consideration. A joint venture is one where two or more parties combine resources for a particular project or business activity. A strategic alliance is a less formal collaboration than a joint venture and doesn't involve creating a new entity. A merger is when two companies combine into one, which could potentially lead to a monopoly if the combined entity were to dominate the market. Lastly, a monopoly exists when a single company has exclusive control over a commodity or service in a particular market, which can be the result of various business maneuvers, including mergers or collusion. Of these options, collusion to create a monopoly would be illegal in many jurisdictions, including the United States.