The correct answer is option 4, Assam. Assam is the Indian state that shares boundaries with the largest number of states in India. Assam shares borders with several states, including Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Meghalaya, and West Bengal.

Option 1, Madhya Pradesh, is incorrect as it shares boundaries with a lesser number of states compared to Assam.

Option 2, Chhattisgarh, is also incorrect as it shares boundaries with fewer states compared to Assam.

Option 3, Maharashtra, is incorrect as it shares boundaries with a limited number of states and does not have as many bordering states as Assam.

It is important to note that while Assam shares boundaries with the largest number of states, it may not necessarily be the state with the longest total length of borders, as the individual border lengths can vary.