Final answer:
Wearing seat belts is not a leading cause of collisions; it is a safety measure. Distracted driving, speeding, and driving under the influence are the actual leading causes.
Step-by-step explanation:
The correct answer to the question of which of the following is not a leading cause of collisions is C) Wearing seat belts. Distracted driving, speeding, and driving under the influence are well-recognized factors that increase the risk of a collision. Wearing seat belts is actually a safety measure that helps protect occupants in the event of a collision and is not a contributing factor to the cause of collisions.