Final answer:
The differences between a vehicle and a bicycle that place the bicyclist at a major disadvantage in any collision are weight and speed.
Step-by-step explanation:
The correct answer is d. weight and speed.
When it comes to collisions, the differences in weight and speed between a vehicle and a bicycle place the bicyclist at a major disadvantage.
The weight of a vehicle is much greater than that of a bicycle, which means that in a collision, the vehicle will exert a stronger force on the bicycle. Additionally, vehicles usually travel at higher speeds than bicycles, which increases the force of impact in a collision.