Answer:
The way that you could set mood with Lights, Set, and Costumes is; Whenever you have got dimmed lights and the set looks like it's raining and the costumes of rain jackets/coats you can infer that the mood is sad.
Expslanation:
Rain usually infers that something sad like a funeral has set a sad mood becasue the rain makes it seem cold and in some cases can even make it kind of spooky. But the main way is that the lights could be dimmed to make a sad effect. Plus I am also in a performing arts class.