Which of the following practices should lifeguards enforce to promote pool hygiene?

Enforcing showering before entry is critical for promoting pool hygiene. This practice helps to remove personal contaminants, such as dirt, sweat, and personal care products, from the bodies of swimmers before they enter the water. By requiring everyone to rinse off, it reduces the introduction of harmful substances into the pool, which can lead to waterborne illnesses and compromised water quality. This simple yet effective measure contributes significantly to maintaining a clean and safe swimming environment for all patrons.

In contrast, the other choices do not directly address pool hygiene. Regular water games and diving competitions can increase water contamination and do not inherently promote cleanliness. Additionally, reducing staff monitoring could lead to a lack of enforcement of hygiene protocols, which may further compromise the safety and health standards of the facility.