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.

Comprehension:
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.

Select the most appropriate option to fill in blank number 1.