Final answer:
The speed limit does not affect the choice of gear in mountain driving. Instead, gear selection is based on maintaining a safe speed, which is influenced by road conditions, vehicle weight, and engine power.
Step-by-step explanation:
In the context of driving a truck down a hill, the gear selection is crucial for maintaining control of the vehicle. When choosing the appropriate gear for mountain driving, several factors come into consideration:
- Road conditions: The state of the road can affect traction and thus influence gear choice.
- Vehicle weight: Heavier vehicles require lower gears to control the descent safely.
- Engine power: The power of the engine can determine how effectively a vehicle can maintain a safe speed using engine braking.
- Speed limit: While it is a factor for road safety and legal compliance, the speed limit itself does not affect the choice of gear. Rather, the gear selection is about maintaining a safe speed that is often lower than the speed limit when descending steep grades.
Therefore, based on the options provided, the one factor that does NOT affect your choice of gear when driving down a slope is the speed limit.