• Reactive Nitrogen Species (RNS): Nitrogen-containing free radicals and reactive molecules:
• Nitric Oxide ($\cdot\text{NO}$): A free radical synthesized from L-arginine by nitric oxide synthases (NOS).
• Peroxynitrite ($\text{ONOO}^-$): A highly reactive and damaging oxidant formed by the diffusion-controlled reaction of nitric oxide with superoxide:

• Reactive Oxygen Species (ROS):
• Superoxide ($\text{O}_2^{\bullet -}$) and (C) Hydroxyl Radical ($\cdot\text{OH}$) are primary reactive oxygen species (ROS) containing oxygen without nitrogen.
• Conclusion: Therefore, (B) and (D) only are reactive nitrogen species.

Correct option: (4) (B), (D) only.