MacMohan line forms the boundary between

The McMahon Line is the boundary between India and China, drawn between British India (Arunachal Pradesh, then NEFA) and Tibet. Sir Henry McMahon proposed it at the Simla Convention of 1914, attended by British India, Tibet and China. China did not accept the final agreement and still rejects the line, so the eastern sector of the India-China boundary remains disputed.

• Pakistan: the India-Pakistan boundary is the Radcliffe Line (1947). The Durand Line is the Afghanistan-Pakistan frontier.
• Myanmar: the India-Myanmar boundary was fixed through separate colonial-era arrangements and later joint demarcation, not the McMahon Line.
• Nepal: the India-Nepal boundary rests on the Sugauli Treaty of 1816 and later surveys. Kalapani is a live dispute, but it is not the McMahon Line.

Mains angle: the McMahon Line underpins the Arunachal Pradesh question in India-China relations. Do not confuse it with the Line of Actual Control, which emerged after 1962 and was addressed in the 1993 and 2013 agreements.

Trap: choosing Pakistan or Nepal because the question reads like a partition-era or treaty question. Anchor it to the Simla Convention of 1914.