Once the teeth start grinding food, is produced to make food moist and slippery.

The answer is saliva. It makes food moist and slippery

Explanation:

answer; /// i believe the answer is (sterilization ) plz check first.good luck

out of the choices i'd say d the ability to set goals, mainly because to desire to continue you need motivation but it isn't motivation in that part, but setting goals means you have an endgame and you want to reach it which sums up motivation.