Which of the following correctly identifies the IUPAC name for a cycloalkane with a six-membered ring and one methyl group attached at the 1-position?

The correct IUPAC name is 1‑methylcyclohexane. In naming, the parent ring is cyclohexane because it has six carbon atoms in a ring. The substituent, a methyl group, is attached to the ring, so we add the prefix “methyl” and specify its position as 1‑. Thus the full name becomes 1‑methylcyclohexane. For example, a molecule with a six‑membered ring and a single methyl group attached would be written as 1‑methylcyclohexane.