Option a is correct because as more and more mergers occur in the market it will be a disadvantage to the joint ventures as they merged with other firms in order to gain more profit. As more and more firms merge it will lead to a decrease in the amount of profit earned by the joint ventures which will lead to a disadvantage of the firm.

Mergers and Monopolistic Activities is a disadvantage of Joint Ventures

Joint ventures refer to a form of business enterprise where two or more entities come together to collaborate and jointly undertake a specific business project or venture. It involves the pooling of resources, expertise, and risks by the participating entities. While joint ventures have their advantages, they also come with certain disadvantages, one of which is the potential for mergers and monopolistic activities.

Mergers:
- Mergers occur when two or more companies combine to form a single entity. In the context of joint ventures, mergers can be a disadvantage because they can lead to a reduction in competition within the market.
- When two or more entities merge in a joint venture, they may gain a significant market share and become dominant in the industry. This can result in decreased competition, which can be detrimental to consumers and other businesses.
- Mergers can lead to higher prices, reduced product variety, and limited consumer choice. This is because the merged entity may have the power to control prices and dictate terms to suppliers and customers.

Monopolistic Activities:
- Monopolistic activities refer to the practices of a company or entity that has a monopoly or dominant position in the market. In the context of joint ventures, monopolistic activities can arise when the participating entities engage in anti-competitive practices.
- Joint ventures may result in the creation of a dominant entity that has the ability to manipulate prices, control supply, and exclude competitors from the market.
- These monopolistic activities can harm consumers by limiting their choices, driving up prices, and stifling innovation and competition.

Conclusion:
In summary, joint ventures can be a disadvantage when they lead to mergers and monopolistic activities. These activities can result in reduced competition, higher prices, limited consumer choice, and a lack of innovation in the market. It is important for regulatory bodies to monitor and regulate joint ventures to ensure fair competition and protect the interests of consumers and other businesses.