In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

Rock candy is actually a collection of large sugar crystals that are "grown" from a sugar-water (1) ______. Crystals form when the smallest particles of a substance, the molecules, arrange themselves in a/an (2) ______ and repetitive pattern. Molecules are too small for us to see moving around and (3) ______ themselves, but you can get a rough idea of what this would look like by taking a small shallow tray and filling it with marbles, ball bearings, or other spheres. As you (4) ______ more spheres, the bottom of the tray becomes covered, then the spheres must form layers on top of (5) ______, and a structure or pattern emerges.