ANS:A - red phosphorus

Red phosphorus is a less reactive and more stable allotrope of phosphorus compared to yellow phosphorus. It is formed by heating white phosphorus in the absence of air or by exposing white phosphorus to sunlight. Red phosphorus is used in safety matches due to its non-toxic nature and lower reactivity compared to yellow phosphorus. In safety matches, red phosphorus is applied to the matchbox surface, and when the match is struck against the surface, the friction ignites the red phosphorus, initiating the combustion of the match head. This process provides a safer alternative to the use of yellow phosphorus, which is highly toxic and poses health hazards.