Answer:
B. overlap of two d orbitals end to end overlap of p orbital.
Explanation:
Sigma bonds are the strongest type of bonds and they are covalent which is due to the direct or end to end overlap of orbitals. The symbol σ is used to adequately describe the bond that exists in a molecule.
In organic molecules, a single C-C bond is a sigma bond while a multiple C-C bond is composed of one sigma bond together with pi or other bonds that is a double bond has one sigma plus one pi bond, and a triple bond has one sigma plus two pi bonds.
Examples include: s-s orbital, pz-pz orbitals, dz-dz orbital and hybrids like sp-p etc.
