The diagram below shows a gear system consisting of a circular gear, Gear A, and a straight vertical rack gear, Gear B.
Gear A is mounted on a fixed axle and can rotate. Gear B can slide up and down.
Gear A has 120 teeth, and the pitch (the distance between successive teeth) on both gears is 1.5 mm.
If Gear A completes exactly 2.5 full revolutions in a clockwise direction, which of the following describes the motion of Gear B?
180 mm180\text{ mm}180 mm down
180 mm180\text{ mm}180 mm up
450 mm450\text{ mm}450 mm down
450 mm450\text{ mm}450 mm up