The correct answer is B. Acquisition.
An acquisition is a business transaction in which one company acquires all or a controlling interest in another company. The acquiring company typically pays a premium to the target company’s shareholders in exchange for their shares. The acquisition can be friendly, in which the target company’s management agrees to the acquisition, or hostile, in which the target company’s management does not agree to the acquisition.
A merger is a business transaction in which two companies combine to form a new company. The new company is typically owned by the shareholders of the two merging companies. The merger can be friendly, in which the management of both companies agree to the merger, or hostile, in which the management of one company does not agree to the merger.
A strategic alliance is a business relationship between two or more companies that agree to cooperate on a specific project or business activity. The strategic alliance is typically non-exclusive, meaning that the companies involved are free to enter into other strategic alliances with other companies.
In the case of the question, the company that takes over another one and clearly becomes a new owner is said to have acquired the other company.