The first answer is correct (A).
Vertical integration consists of companies that acquire a similar company in the same industry. That is, if a company wants to grow through horizontal integration, it will seek to increase its size by incorporating other companies and their respective assets.
If a company is incorporated, of course the market loses a company, that is, the competition decreases.
It is noteworthy that vertical integration needs to be authorized by a regulatory antitrust policy, such as the Federal Trade Commission - FTC.
