Equal volumes (5 mL each) of hexane (density 0.66 g mL⁻¹), ethanol (density 0.79 g mL⁻¹), and water (density 1.00 g mL⁻¹) are shaken together in a test tube and allowed to stand. Which sequence correctly describes the layers that will be present from top to bottom after equilibrium is reached?
a) Hexane layer on top; ethanol layer in the middle; water layer on the bottom
b) A single homogeneous layer containing all three liquids
c) Hexane layer on top; a single ethanol–water layer on the bottom
d) Mixed hexane–ethanol layer on top; water layer on the bottom