(C)

Acetylene shows a triple bond between the 2 carbons, which contains 2 pi bonds. In multiple bonds, the first bond is a sigma bond, where electrons are shared along the internuclear axis. Any additional bonding is created by the sideways overlap of unhybridized p-orbitals above and below the internuclear axis. None of the other options for answers contain multiple covalent bonds between any 2 atoms.