Which of the following is NOT one of the five keys to avoiding target indicators?

C is the correct choice because maintaining a loud presence directly contradicts the principles of avoiding target indicators. Target indicators are factors that can reveal a unit's location or intentions to the enemy, and one of the essential strategies for enhancing stealth and operational security is noise discipline. This involves keeping noise levels to a minimum to avoid detection.

The other options are vital components of maintaining stealth in a combat situation. Camo/concealment involves using camouflage techniques to blend into the environment, while covering all reflective material helps minimize visibility and the potential for light reflection that could provide clues about a unit's position. Together, these strategies strengthen operational security and decrease the likelihood of detection by adversaries.