Which of the following might be contained in stage direction A. Lines spoken by a narrator B. A speech by the main character C. A description that tells what the stage looks like D. A summery of the play

Stage directions are small lines put into the script (often in italics) that give the reader an idea of potential movement, what's going on in the scene, what other characters may be experiencing or the expression one may see on their faces. That would mean C is the best possible answer here.