Step 1: Understanding the Concept:
International boundary lines are established through historical treaties and agreements to delineate the sovereign territories of neighboring countries.
Step 2: Detailed Explanation:
The McMahon Line is the effective boundary between China and India in the eastern sector.
It was negotiated and drawn by Sir Henry McMahon during the 1914 Simla Convention between British India and Tibet.
Let us review the other options:
Option (A) Radcliffe Line separates India and Pakistan (as well as India and Bangladesh).
Option (C) Durand Line separates Pakistan and Afghanistan.
Option (D) Line of Control (LoC) is the military control line between the Indian and Pakistani controlled parts of the former princely state of Jammu and Kashmir.
Step 3: Final Answer:
The McMahon Line separates India and China.