The correct option is A It occurs on a deforested site.
Secondary succession or subsere is ecological succession that takes place in a recently denuded area which still contains a lot of organic debris, remains and propagules of previous living organisms. It is more common and caused by baring of an area due to forest fires, deforestation, excessive overgrazing, landslides, earthquakes, repeated floods etc. Only 50-100 yrs are required for establishment of a grassland over a recently denuded area. formation of forests requires 100-200 yrs.