<span>when temperature varies:
volume & temperature vary directly @ constant pressure,... Charles' law
pressure & temperature vary directly @ constant volume,... Gay-Lussac's law
when temp is consatnt:
Pressure & volume vary inversely , ...Boyle's law
Hope This Helped! :3</span>
Everything I'm reading says that both Gneiss AND Schist has a nonfoilated texture. Try one of them, sorry.
The answer is the letter “c”