The correct answer is option 1, Red Phosphorus. Red Phosphorus is a substance used in the manufacture of safety matches. Let`s understand why this is the correct answer.

Option 1: Red Phosphorus is a more stable form of phosphorus compared to white phosphorus. It is non-toxic and less flammable. Red Phosphorus is commonly used in safety matches because it is less hazardous and safer to handle.

Option 2: White Phosphorus is a highly reactive and toxic form of phosphorus. It is used in incendiary devices and military applications. However, it is not used in the manufacture of safety matches due to its high flammability and toxicity.

Option 3: Phosphorus Trioxide (P2O3) is a compound formed by the combination of phosphorus and oxygen. It is not directly used in the manufacture of safety matches and is not a suitable substance for that purpose.

Option 4: Black Phosphorus is another stable form of phosphorus, similar to red phosphorus. However, it is not commonly used in the manufacture of safety matches.

In conclusion, red phosphorus is the correct substance used in the manufacture of safety matches due to its stability, non-toxicity, and