How do the commas in the passage below help the reader read more fluently? Through this endeavor, he met Nancy Newhall, a historian, museum administrator, and a writer-designer, with whom he developed a lifelong friendship.
a.
separates different professions
c.
describes Nancy Hall
b.
slows reader down
d.
all of the above

Please select the best answer from the choices provided

A
B
C
D