Until 1973 homosexuality was considered a psychological disorder american psychological association. which sociological perspective would be most concerned with why this was considered an illness, and what effect that diagnosis had on society?

The answer is Symbolic interactionist.
Symbolic interactionist refers to a sociological perspective which attempts to understand how individuals interact with one another using symbolic gestures and how it could contribute to the formation of pragmatism method to analyze social situations (such as same sex relationship)