The correct option is A Protonema
The complex internal structure of the capsule has three distinct regions. viz., apophysis, theca, and apical region. The sporophyte body comprises a long stalk, called a seta, and a capsule capped by a cap called the operculum. The capsule and operculum are in turn sheathed by a haploid calyptra which is the remains of the archegonial venter. The calyptra usually falls off when the capsule is mature. Within the capsule, spore-producing cells undergo meiosis to form haploid spores, upon which the cycle can start again. The mouth of the capsule is usually ringed by a set of teeth called peristome. Protonema is formed after germination of moss capsule spores and is not a part of the capsule. Thu, the correct answer is B