The correct answer is: a) United Andhra Pradesh.
The merger of the Telangana region with the Andhra state in 1956 created the state of United Andhra Pradesh. The merger was a result of the States Reorganisation Act, 1956, which was passed by the Indian Parliament. The Act was aimed at reorganizing the states of India on a linguistic basis.
The Telangana region was a part of the Hyderabad State, which was ruled by the Nizam of Hyderabad. The Andhra state was a part of the Madras Presidency, which was ruled by the British. The merger of the two regions created the state of United Andhra Pradesh.
The merger was not without its problems. There was a lot of opposition to the merger from the people of Telangana. They felt that they were being discriminated against by the people of Andhra. The opposition led to a lot of violence and unrest in the region.
Despite the problems, the merger of the Telangana region with the Andhra state was a major step in the development of the Indian state. It helped to bring together two different regions and cultures. It also helped to promote peace and harmony in the region.
The other options are incorrect. Option b), Telangana, is incorrect because Telangana was a region that was merged with the Andhra state to create the state of United Andhra Pradesh. Option c), Rayalaseema, is incorrect because Rayalaseema is a region that is part of the state of Andhra Pradesh. Option d), Madras State, is incorrect because Madras State was a state that was dissolved in 1956 and its territory was divided between the states of Andhra Pradesh, Karnataka, and Kerala.