The correct option is B is a stage of gametophytic generation.
The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages.
The first stage is the protonema stage, which develops directly from a spore. It is a creeping, green, branched and frequently filamentous stage.
The second stage is the leafy stage, which develops from the secondary protonema as a lateral bud.