Which of the following is an example of a common explosive?

TNT (trinitrotoluene) and PETN (pentaerythritol tetranitrate) are well-known examples of common explosives due to their widespread use in both military and industrial applications. These substances are characterized by their ability to release a large amount of energy in a very short period when they undergo a rapid chemical reaction, resulting in an explosion.

TNT is famously used in military ordnance and demolition, while PETN is often utilized in detonating devices and some types of military explosives. Their properties make them effective for controlled detonations, which is why they are often studied and recognized in contexts relating to explosives.

In this context, while other choices might involve materials that can also create explosive effects, such as ammunition or fireworks, they do not represent the same level of potency and are not classified strictly as conventional explosives in the same way TNT and PETN are. Therefore, the inclusion of TNT and PETN as a specific and notable example of common explosives is why this choice is the correct answer.