Geet Sethi has made a mark in

Billiards
Shooting
Chess
Golf

Geet Sethi is an Indian professional billiards player. He is the former world champion in three-cushion billiards, having won the title in 1998, 2004, and 2014. He is also a former Asian champion and a multiple-time national champion.

Billiards is a family of cue sports that originated in Western Europe in the 15th century. The game is played on a rectangular table with six pockets, and the object is to pocket balls using a cue stick. There are many different variations of billiards, but the most common are pool and snooker.

Shooting is a sport in which participants use firearms to hit targets. There are many different types of shooting sports, including target shooting, skeet shooting, and trap shooting. Shooting is a popular sport both recreationally and competitively.

Chess is a two-player board game played on a checkered board with 64 squares arranged in an eight-by-eight grid. The game is played by millions of people worldwide. The objective of the game is to checkmate the opponent’s king, whereby the king is under immediate attack (in “check”) and there is no way to remove it from attack.

Golf is a club-and-ball sport in which players use various clubs to hit balls into a series of holes on a course in as few strokes as possible. Golf is played on a variety of courses, ranging from public courses that are open to everyone to private courses that are only open to members.

In conclusion, the correct answer to the question “Geet Sethi has made a mark in” is A. Billiards.