Which sentence uses dashes correctly?

A"I would not step there if I were—!" she began as I slipped on the wet floor.

BSeveral birds stayed at the feeder—hoping for a good meal.

CTurquoise beads and—a silver medallion—adorn her favorite necklace.

D. My sister—a big fan of the outdoors—walks two miles—every afternoon.

(Leaning more towards A., though I'm not sure.)