Which one of the following substances used in the manufacture of safety matches

Red phosphorus is the primary substance used in the manufacture of safety matches. Unlike white phosphorus, which is highly reactive, toxic, and spontaneously ignites in air, red phosphorus is a stable, non-toxic allotrope [t2][t6]. In safety matches, red phosphorus is typically found on the striking surface (ignition strip) rather than the match head itself [t4][t6]. When the match head, containing an oxidizing agent like potassium chlorate and a fuel like sulfur, is struck against the red phosphorus strip, friction converts a tiny amount of red phosphorus into white phosphorus vapor [t6]. This vapor ignites, starting the combustion of the match [t6]. Historically, white phosphorus was used in 'strike-anywhere' matches, but it was phased out due to its extreme toxicity and the industrial disease 'phossy jaw' [t5][t6]. Black phosphorus and phosphorus trioxide are not used in match manufacturing [t1][t3].

Sources

1. [1] https://en.wikipedia.org/wiki/Red_phosphorus
2. [2] https://www.atsdr.cdc.gov/toxprofiles/tp103.pdf
3. [3] https://en.wikipedia.org/wiki/Allotropes_of_phosphorus
4. [4] https://www.ncbi.nlm.nih.gov/books/NBK598124/