The correct answer is: a) Beating Retreat.
The Beating Retreat ceremony is a daily military ceremony held at the Wagah border between India and Pakistan. The ceremony is held at sunset and is a symbolic lowering of tensions between the two countries. The ceremony involves a parade of soldiers from both countries, who march back and forth across the border, accompanied by music and flag-waving. The ceremony ends with the lowering of the flags of both countries and the sounding of a bugle call.
The other options are incorrect because they do not describe the Beating Retreat ceremony.
Option b) Flag hoisting is a ceremony that is held at sunrise, not sunset.
Option c) Military parade is a ceremony that is held on special occasions, not daily.
Option d) Light and sound show is a tourist attraction that is not a military ceremony.