The scenario refers to Galen's theory of the four temperaments, specifically the sanguine type characterized by an easygoing and carefree nature. Galen was a significant figure in ancient medicine, and his theories influenced personality psychology. Therefore, the answer is C. Galen.
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The correct historical theorist described in the scenario is Galen.
Galen was an ancient Greek physician and philosopher whose theories were very influential in the development of medicine and psychology. One of Galen's significant contributions was his work on the four humors, which were believed to affect human temperament and health. These four humors were blood, phlegm, yellow bile, and black bile, and each was associated with a different temperament:
Sanguine : Associated with the humor of blood, characterized by an optimistic and social personality.
Choleric : Characterized by being ambitious and leader-like, associated with yellow bile.
Melancholic : Linked to black bile, characterized by being analytical and detail-oriented, sometimes leading to sadness.
Phlegmatic : Related to phlegm, characterized by a relaxed and quiet demeanor.
In the given scenario, an easygoing, carefree person is described as sanguine. This directly ties to Galen's theory, where someone with a sanguine temperament is expected to be outgoing and sociable. Therefore, the answer is Galen.