thin flaky sheets and very hard glassy texture and a shiny black color very rough texture with obvious crystals sand-sized particles and a light brown color
I gave my students this multiple choice question: During a walk through the Arkansas River Valley, Alex found a rock that she determined was a sedimentary rock. Which characteristics of the rock would lead Alex to this conclusion?

Only one answer is correct among these 4 choices:
- thin flaky sheets and very hard
- glassy texture and a shiny black color
- very rough texture with obvious crystals
- sand-sized particles and a light brown color

Could you tell me which one is correct?

sand-sized particles and a light brown color