Answer the following question given this paragraph: 

Some solids are not crystals. Glass, or the rock obsidian, are solid. However, they are not crystals. In a crystal , the atoms are arranged in a pattern. This pattern is regular and it repeats. The image below shows how the atoms are arranged in halite (table salt) ( Figure below ). Halite contains atoms of sodium and chlorine in a pattern. Notice that the pattern goes in all three dimensions.


Q: What type of solid has atoms arranged in a repeating pattern?

 Choices:

- ions

- metals

- hydrocarbons

- crystals

A:
crystals
