What is the MAXIMUM slope for a ramp?

The maximum slope for a ramp is defined by standards such as those set by the Americans with Disabilities Act (ADA). According to these standards, the recommended slope for accessible ramps is 1:12, meaning that for every inch of vertical rise, there should be at least 12 inches of horizontal run. This ratio translates to a maximum slope of 1 unit vertical for every 12 units horizontal.

The correct choice provides a slope that adheres to this regulation, making it the most compliant option. Therefore, a slope of 1 unit vertical in 8 units horizontal fails to meet these guidelines, as it indicates a steeper incline (1:8) that would not be safe or accessible for individuals using mobility devices.

On the other hand, the choices involving greater vertical rises in relation to their horizontal spans, such as 2 units vertical in 12 units horizontal or 2 units vertical in 18 units horizontal, still do not comply with the maximum allowable slope as they make the ramps even steeper than the ideal recommendation set forth.

Thus, while the 1:12 slope is the standard, the choice of 1 unit vertical in 12 units horizontal is the ideal to ensure both compliance and safety in ramp design.