Answer: side by side overlap of two p orbital---B
Step-by-step explanation: pi bonds denoted by Greek letter , π are covalent chemical bond where there is a side-by-side overlap of two p orbitals laterally illustrated by when two lobes of an orbital on one atom overlap two lobes of an orbital on the other atom.
At the shared nodal plane of the overlapping orbitals, there exists an electron density which is equal to zero which also serves as a nodal plane for the molecular orbital of the pi bond. Double and triple bonds contain one sigma bond with one or two pi bonds between atoms.