Final answer:
Red phosphorus is a reactive flammable material used in safety matches, fireworks, and smoke bombs, and is less reactive and less toxic than white phosphorus.
Step-by-step explanation:
Red phosphorus is a less reactive allotrope of phosphorus compared to white phosphorus, and it is classified as a reactive flammable material. Heating white phosphorus in the absence of air changes it into red phosphorus, which is much less reactive, essentially nontoxic, denser, and has a higher melting point (around 600 °C). Red phosphorus is used in safety matches, fireworks, and smoke bombs due to its flammable nature, but it does not exhibit the same level of danger in terms of reactivity as white phosphorus, which can spontaneously ignite in air. Therefore, the correct answer is C) reactive flammable material.