The value of slope provided to the wheels is given as 1 in 20.

Explanation:
To understand the value of slope provided to the wheels, let's first understand what is meant by "1 in 20" slope.

A slope is a measure of how steep a surface is and is usually expressed as a ratio of vertical rise to horizontal run. In the case of "1 in 20" slope, it means that for every 20 units of horizontal distance traveled, there is 1 unit of vertical rise.

Now, let's discuss why option B is the correct answer.

1. Slope Measurement:
The value of slope is measured by comparing the vertical rise to the horizontal run. In this case, the slope is given as 1 in 20, which means that for every 20 units of horizontal distance, there is 1 unit of vertical rise.

2. Wheel Movement:
When a vehicle moves on a slope, the wheels experience the slope's inclination. This inclination affects the vehicle's traction and stability. The steeper the slope, the more challenging it becomes for the wheels to maintain grip and prevent slippage.

3. Optimal Slope:
To ensure safe and efficient movement, it is crucial to provide an optimal slope to the wheels. If the slope is too steep, the wheels may lose traction and result in accidents or difficulties in vehicle movement. On the other hand, if the slope is too gentle, it may not provide sufficient vertical rise to overcome obstacles or assist in vehicle control.

4. Option B: 1 in 20 Slope:
Among the given options, option B provides a slope of 1 in 20. This means that for every 20 units of horizontal distance, there is 1 unit of vertical rise. This slope strikes a balance between providing enough vertical rise for vehicle control and stability while not being overly steep to cause slippage or difficulties in movement.

Therefore, option B, which provides a slope of 1 in 20, is the correct answer.

In conclusion, the value of slope provided to the wheels is 1 in 20. This slope allows for safe and efficient movement of vehicles by providing an optimal balance between vertical rise and horizontal distance traveled.