The correct answer is A. Graphite.
In graphite, each carbon atom is bonded to three other carbon atoms in a hexagonal lattice. This means that each carbon atom is quaternary, or bonded to four other atoms.
Diamond is also made of carbon atoms, but they are arranged in a tetrahedral structure. This means that each carbon atom is bonded to four other carbon atoms, but only three of those bonds are covalent. The fourth bond is a weak van der Waals bond.
Teflon is a polymer made of carbon and fluorine atoms. The carbon atoms are bonded to four fluorine atoms, so they are also quaternary.
Naphthalene is a hydrocarbon with the formula C10H8. It is a white, crystalline solid that is found in coal tar. The carbon atoms in naphthalene are bonded to two other carbon atoms and two hydrogen atoms. This means that they are secondary, or bonded to two other atoms.
Therefore, the only substance in which all carbon atoms are quaternary is graphite.