The correct options are
A Battle of Plassey
B Battle of Buxar
D Development of Calcutta as capital city.
After the battle of Plassey in 1757 and the battle of Buxar in 1764, the city of Murshidabad lost its importance.
Murshidabad was the capital of the Nawab of Bengal.
As the Nawas lost the battle the city lost its importance.
The British made Calcutta their administrative centre and with the expansion of the British political power, the British centres of administration also gained importance.