What does the term "proscenium" refer to in theatre design?

Question

a
The extended portion of the stage that projects towards the audience.
b
The enclosed space that separates the performers and the audience.
c
The raised stage and semicircular seating area in ancient Greek theatre.
d
The arch or rectangular opening between the stage and the audience seating area in a proscenium theatre.

Answer 1

The term "proscenium" refers to d. The arch or rectangular opening between the stage and the audience seating area in a proscenium theatre. This architectural feature frames the stage and separates the actors from the audience, providing a distinct boundary for the performance.