Question

what is a gear train?
one gear that is moved to different places on a robot between builds
a mechanism made up of two or more gears
a type of vex iq robot
a type of force

Explanation:

A gear train is a mechanical system. It consists of multiple gears. These gears mesh together. Their combination serves a specific function. The key is the number of gears (two or more).

Answer:

A mechanism made up of two or more gears.