Please Help What does this online dictionary entry suggest about the etymology of the word theater?

theater
/'THēədər/
noun

1 a: a building or area for dramatic performances
b: a building or area for showing motion pictures
c: an outdoor structure for dramatic performances or spectacles in ancient Greece and Rome

A. The word changed from a noun to an adjective.
B. The word was introduced by the Vikings.
C. The word is Greek in origin.
D. The word's meaning has changed a lot over time..