Explanation:

First is correct. In 19th century, the British gradually created a series of buffer states along the land boundary of the empire which was called the “ring fence”.
Wellesley's policy of subsidiary alliance was an extension of ring fence—which sought to reduce states to a position of dependence on British Government in India. Major powers such as Hyderabad, Awadh and the Marathas accepted subsidiary alliance.
Second is correct. The British Government adopted the policy of subordinate union towards Indian princely states from 1857 to 1835. The policy of annexation was abandoned by them and right to adopt heir was accepted. The Act of 1858 transferred powers into the hands of the crown.
Third is correct. In the policy of subordinate isolation princely states were supposed to cut in super domes cooperation with the British Government and acknowledge its supremacy.
Fourth is incorrect. Policy of Integration and Merger was not pursued by the British government in context of Indian Princely states.