Final answer:
The essential food groups for a healthy diet include vegetables, fruits, grains, proteins, and dairy, providing necessary nutrients; junk food is not part of these groups.
Step-by-step explanation:
Discussing the importance of eating a healthy diet is vital, as it involves consuming a variety of nutrients essential for good health from all food groups. A balanced diet includes a mix of vegetables, fruits, grains, protein foods, and dairy, which provides the body with vitamins, minerals, protein, carbohydrates, fats, and fibers needed for proper functioning. Junk food, which is high in sugar, salt, and unhealthy fats, does not belong to the essential food groups and is not necessary for a healthy diet. Among the options given, Junk food (C) is NOT one of the essential food groups.