Solid material whose atoms are arranged in a repeating pattern is

crystal structure

Explanation:

A crystal structure is an ordered arrangement of atoms,ions or molecules in a regular repeating pattern,it is a form of solid state of matter and differs from liquid and gaseous states of matte in which the atoms or molecules are random or haphazard.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.