Which sociological perspective/theory stresses that society is a whole unit, made up of interrelated parts that work together harmoniously?

Answer: Structural functional perspective/theory

Explanation: Structural functional perspective/theory is a school of thought that view society as a complex entity but with interconnected system which each area (part) work hand in hand harmoniously. Metaphorically speaking, it views society like the human body which has the hands, legs, brain, ears, eyes, heart and all the human body parts you can think of, each part has is own system for working and work specification but still each has to work harmoniously for a fully functional human body system.