Final answer:
Without context, it's impossible to determine who the art department head is among the options given. The references provided from 'Introduction to Art History I' do not contain this information.
Step-by-step explanation:
The question "Who is the art department head and supervises the art staff?" seems to relate to a specific organization or school's art department, which is not detailed in the information provided. Taking the details from the introduction to 'Art History I' as a reference, where Cerise Myers is indicated as the Textbook Project Lead, Principal Writer and Editor, and Ellen C. Caldwell as the Assistant Project Lead, Principal Writer and Editor, it is not possible to accurately determine who the department head is among Phillip, John, Sarah, and Emily without additional context.
Assuming this question pertains to a hypothetical or case-study situation detailed in a textbook or course materials, the answer would be found by referencing that material directly. However, based on the information provided, no accurate answer can be given to this question.