What is the explanation for the strange spelling of the English word "playwright"?

a. During the Elizabethan period, all authors were known as "wrights."
b. A mistake made early in the history of printing became standard.
c. Its origin is the German word for "author."
d. During the Middle Ages, "wright" meant a craftsperson.

d. During the Middle Ages, "wright" meant a craftsperson.