Which of the following is NOT one of the four primary skills that lifeguards must master?

The selection of "Marketing techniques" as the answer highlights the focus on the essential competencies that lifeguards need to effectively perform their duties. The four primary skills lifeguards must master—surveillance, rescue techniques, and first aid—are critical for ensuring the safety of patrons in aquatic environments.

Surveillance is vital for identifying potential dangers and monitoring swimmer behavior. Lifeguards must be adept at observing the water and its users to detect emergencies before they escalate.

Rescue techniques encompass the procedures and physical methods employed to save a drowning or distressed swimmer, which can include various types of assists and rescues depending on the situation.

First aid knowledge is equally crucial, as it equips lifeguards with the skills to provide immediate care in the event of injuries or medical emergencies until professional help arrives.

While marketing techniques might be useful for promoting lifeguarding programs or facilities, they do not pertain to the direct responsibilities and critical life-saving skills that are the focus of lifeguard training. Thus, marketing techniques do not belong to the core competencies necessary for a lifeguard role.