Final answer:
Slate and hornfels are both associated with contact metamorphism, with hornfels being the definitive rock type for this process, leading to the correct answer of D) B and C.
Step-by-step explanation:
The rocks that may be associated with contact metamorphism include slate and hornfels. While gneiss is a high-grade metamorphic rock typically associated with regional metamorphism, slate is a lower-grade metamorphic rock that can also form in contact metamorphic zones. However, hornfels are the definitive rocks of contact metamorphism, as they are formed from the baking by heat of intrusive igneous masses at relatively high temperatures but low pressure, resulting in nonfoliated rocks that are quite durable.
Therefore, options B) slate and C) hornfels are associated with contact metamorphism. This leads us to the correct answer being D) B and C.