Which of these is NOT a player class in Team Fortress 2?

The answer is Healer because there is no specific healer class in Team Fortress 2. Unlike games like Overwatch or World of Warcraft, Team Fortress 2 focuses more on fast-paced, objective-based gameplay rather than having dedicated healers. Each class has its own unique abilities and specialties, such as the Medic's ability to heal teammates, but they are primarily focused on offense, defense, or support through damage output rather than solely healing.