"Adolescence is the period of great stress, strain, storm and strike" is the…

Concept: The “Storm and Stress” (Sturm und Drang) view is an early developmental-psychology framework describing adolescence as a stage of pronounced emotional turbulence, tension, and conflict, arising from the rapid physical, cognitive, and social change that accompanies the transition from childhood to adulthood.

Application: The description quoted here, an age of great stress, strain, storm and strike, is precisely this storm-and-stress characterisation, propounded by G. Stanley Hall (1904), regarded as the father of the scientific study of adolescence — so the statement belongs to him.

Cross-check, why the other names do not fit:

• Crow & Crow described adolescence as a period of transformation and adjustment from childhood to adulthood, marked by physical, mental, emotional, and social change, not by this storm-and-stress phrasing.

• Jersild's work centres on the adolescent's self-concept and emotional and personal development, a different framing from this statement.

• Simpson is not associated with this characterisation; his contribution to child and educational psychology addresses different themes.

Hence, the statement is correctly attributed to Stanley Hall.