Answer:
B. Introspection
Step-by-step explanation:
Structuralism, in psychology, as founded by Wilhelm Wundt sought to analyze and in essence break down(hence structuralism) the adult mind into basic elements for the purpose of his study of the brain and it's functions. It defined the mind as the sum total of experience from birth to present, and sought to relate the different functions of the mind to physical events.
The major tool of structuralist psychologists was introspection- careful observation of thought processes and feelings which is made amid controlled conditions and done by trained observers applying stringently defined descriptive vocabulary.