Which two humors did Claudius Galen identify as necessary for maintaining balance and health?

Claudius Galen, a prominent physician in ancient Rome, built upon the earlier theory of the four bodily humors that originated from Hippocratic medicine. He identified black bile and yellow bile as two of these critical humors.

According to the humorism doctrine, each humor was associated with specific qualities and imbalances among them were thought to affect an individual's health and temperament. Black bile was linked to the earth element and was believed to contribute to melancholic temperaments, while yellow bile was associated with the fire element, equating to a choleric disposition. The balance of these humors was considered essential for overall health, informing early understandings of disease and wellness.

The options that reference blood, plasma, phlegm, serum, white bile, and red bile either misinterpret Galen’s theory or introduce concepts not attributed to him. Overall, the identification of black bile and yellow bile as requisite humors illustrates the foundational ideas in humoral theory that influenced medical practice and philosophy for centuries.