Correct Answer: (b) Indo-Pakistan boundary line
Solution:India has natural as well as man-made boundaries. Himalaya in the north, Bay of Bengal in the south-east, Indian Ocean in the south and Arabian sea in the south-west forms its natural boundary. India shares its border with China (Tibet), Bangladesh, Afghanistan, Pakistan, Bhutan, Nepal, Maldives, Sri Lanka and Myanmar. Radcliffe line demarcates the border between India and Pakistan and Macmahon line between India and China. Durand line demarcates the border between India and Afghanistan. Sri Lanka is separated from India by the Palk Strait. It is about 64-137 km wide. It was named after the then Governor of Madras Robert Palk.