The correct answer is A. 1956.
The Municipal Corporation of Shimla was established in 1956 under the provisions of the Municipal Corporation Act, 1956. The corporation is responsible for the administration of the city of Shimla. It has a mayor and a council of councilors who are elected by the people of Shimla. The corporation is also responsible for providing basic services such as water supply, sanitation, and electricity to the people of Shimla.
Option B is incorrect because the Municipal Corporation of Shimla was not established in 1970.
Option C is incorrect because the Municipal Corporation of Shimla was not established in 1951.
Option D is incorrect because the Municipal Corporation of Shimla was not established in 1957.