Buna-`N` synthetic rubber is a copolymer of:
A. `H_(2)C = CH -overset(Cl)overset(|)(C) = CH_(2) and H_(2)C = CH - CH = CH_(2)`
B. `H_(2)C = CH - CH = CH_(2) and H_(5)C_(6) - CH = CH_(2)`
C. `H_(2)C = CH - CN and H_(2)C = CH - CH = CH_(2)`
D. `H_(2)C = CH - CN and H_(2)C = CH - underset(CH_(3))underset(|)(C) = CH_(2)`