Which equipment is essential for a lifeguard on duty?

The essential equipment for a lifeguard on duty includes lifesaving tools and resources that enable quick and effective responses in emergencies. This includes lifeguard rescue tubes, which are critical for assisting distressed swimmers, allowing lifeguards to safely pull individuals to safety. First aid kits are vital as they contain necessary supplies for treating injuries or medical emergencies that may occur at aquatic facilities. Additionally, communication devices, such as radios or whistles, facilitate rapid coordination with other lifeguards and emergency services, ensuring that help can be summoned promptly when needed.

In contrast, the other options provided do not encompass the fundamental lifesaving resources. For example, while whistles and towels are useful, they do not offer the same level of support for emergency situations as the items in the correct answer. Similarly, items such as flippers and diving masks are typically associated with recreational swimming rather than lifesaving efforts, and floatation rings or pool noodles, while they can aid in safety, are not as critical as the rescue equipment and communication tools listed in the correct answer.