Final answer:
A wheel is more prone to slip on a steep incline than on a gently sloped incline due to the increased requirement for static friction to prevent slipping.
Step-by-step explanation:
A wheel that is released from the top on an incline is most likely to slip if the incline is steep. This is because the component of the wheel's weight that is parallel to the incline increases as the incline becomes steeper, which requires a larger static friction force to keep the wheel from slipping. The maximum static friction force is determined by the coefficient of static friction and the component of the wheel's weight perpendicular to the slope. If the incline is too steep, the required static friction may exceed the available static friction, leading to slippage. Therefore, for a wheel released on an incline, slippage is more likely to occur on steeper slopes compared to gently sloped inclines.