Elements on the periodic table of the elements are classified into categories such as

1) rocks and minerals
2) molecules and atoms
3) mixtures and compounds
4) metals and nonmetals

im pretty sure its 2, but can someone clarify?

4- Metals and nonmetals

I don't believe there are any "rocks" per se on the table. Everything on the table is an atom, there are no molecules. In addition, none of them are mixtures and compounds.

This leaves metals and nonmetals. The periodic table is usually colored in different sections. Elements such as Cobalt are metals, and they're grouped with other metals like Technetium. Metals and nonmetals are the broadest forms of classification, since there are multiple kinds of metals (alkaline, rare earth) and nonmetals (noble gases, etc.)