A swimming pool fence must prevent the passage of a sphere that is larger than what size?

The requirement for a swimming pool fence to prevent the passage of a sphere larger than 4 inches is based on safety standards aimed at protecting young children from drowning. This dimension is critical because if a child can fit through a gap in the fencing, they can potentially gain access to the pool area, increasing the risk of accidents.

The 4-inch measurement is specifically chosen because it is small enough to ensure that children under a certain age, who typically have smaller bodies, cannot slip through the openings. This standard helps ensure that the fence provides an effective barrier, which is a key aspect of pool safety regulations.

Higher dimensions, like those mentioned in the other choices, would not adequately account for the sizes of young children and their potential access to a pool area if a fence is improperly designed. Hence, ensuring that the openings in a fence do not exceed 4 inches is a crucial preventive measure in safeguarding children from the hazards associated with swimming pools.