What role does a motorcycle's rear sprocket play in torque modification?

The rear sprocket plays a crucial role in modifying the torque delivered to the motorcycle's rear wheel by influencing the overall gear ratios. When the size of the rear sprocket changes, it directly affects how the engine's power is transmitted to the wheels. A larger rear sprocket increases torque at the wheel, which can improve acceleration and responsiveness, while a smaller rear sprocket reduces torque but can increase top speed.

By altering the gear ratios, the rear sprocket can enhance the balance between low-end torque and high-end power. This adjustment allows riders to customize their motorcycle's performance based on their preferences and riding conditions, whether they need more low-end power for quick acceleration or higher speeds for cruising.

In contrast, the other options do not accurately describe the function of the rear sprocket. Fuel efficiency is influenced by various factors like engine tuning and riding style, but it is not a direct result of changes to the rear sprocket. The engine type is unrelated, as it pertains to the underlying architecture and mechanics of the motorcycle's engine itself, rather than the final drive system. Tire pressure, while critical for performance and handling, does not have a direct relationship with the gear ratios established by the rear sprocket.