Answer : The correct option is, atoms or molecules that are closely spaced but are free to move around and past each other.
Explanation :
Amorphous Solids : It is a type of solids where the constituent particles of the matter are arranged in the random manner. That means there is no proper arrangement of atoms in solid lattice but the atoms or molecules are closely spaced that means they can move freely from one place to another. They do not have long range.
The examples of amorphous solid are, plastics, glass, rubber, metallic glass, polymers, gel, fused silica, pitch tar, thin film lubricants, wax.
Crystalline Solids : It is a type of solids where the constituent particles of the matter are arranged in the specific manner. That means there is a proper arrangement of atoms in solid lattice. They do not have space between the molecules or atoms and they can not move freely from one place to another.
The examples of crystalline solids are, quartz, calcite, sugar, mica, diamonds, snowflakes, rock, calcium fluoride, silicon dioxide, alum.
Hence, an amorphous solid is the result of atoms or molecules that are closely spaced but are free to move around and past each other.