Gear a is the driving gear. if all the teeth are sheared off of gear b which gears will turn

Gear a

Explanation:

Gears are pairs of rotating elements which transmit torque to the one another. Each gears have teeth on them and they mesh together to transfer rotary motion from one shaft to the the shaft. Gears can change the power, speed and the direction of power source.

In the context, it is given that gear a is the driving gear. If the gear a meshes with gear b, gear a will rotate gear b. Hence gear a is the driving gear and gear b is the driven gear. Thus gear b gets its motion from gear a.

Now if the teeth of gear b are sheared, then gear b will not be able to mesh with gear a and thus gear b ceases to stop its motion.

Thus gear a will turn.