Manjeet Kaur excelled in the 4 × 400 m women relay race at the Doha Asiad-2006. In this event, teams of four runners take turns to complete a total distance of 400 meters. Each runner runs one lap around the track before passing on the baton to the next runner. The relay race requires a combination of speed, stamina, and teamwork.

Option 1, the 100 m race, is a single sprint event where athletes run a straight 100-meter distance. This is a different event from the relay race.

Option 3, shooting, is a completely different sport that involves accuracy and precision in hitting targets with firearms. It is not related to Kaur`s achievement at the Doha Asiad-2006.

Option 4, discus throw, is a field event in athletics where athletes throw a heavy discus as far as possible. This is also unrelated to Kaur`s success in the relay race.

Therefore, the correct answer is option 2, the 4 × 400 m women relay race.