The correct option is D The British would protect the Indian states against any foreign attack or internal revolt.
Features of the Subsidiary Alliance Treaty are:
-An Indian ruler entering into Subsidiary Alliance with the British had to dissolve his own armed forces and accept British forces in his territory.
-He also had to pay for the British army’s maintenance. If he failed to make the payment, a portion of his territory would be taken away and ceded to the British.
-The British would protect the Indian state against any foreign attack or internal revolt.
-The Indian state could not enter into any alliance with any other foreign power.
-The Indian state could also not enter into any political connection with another Indian state without British approval.