Explanation : (D) Hall introduced the concept of adolescence as a transitional period in human experience, characterised as rebellious behaviour and biological maturation occurs between the age of 14 to 24.
Explanation : (A) Wilhelm Wundt, a German doctor and psychologist, established world's first experimental psychology lab in 1879 at the university of Leipzig, Germany. He is widely regarded as the "father of experimental psychology".
Explanation : (B) Gestalt school of psychology was founded in the early 20th century by the German psychologist Max Wertheimer and his younger colleagues, Kurt Koffka and Wolfgang Kohler.