The correct option is D Gemmae are reproductive structures.
Asexual reproduction in some bryophytes like the liverworts take place by the formation of gemmae. Gemmae are bud-like mass of undifferentiated tissue which helps in asexual (vegetative) reproduction.
Bryophytes are called the 'amphibians of the plant kingdom' because they can live on land but are dependent on water for fertilisation. The plant body is thallus-like and lack true root, stem, or leaves. It bears gametes, hence it is called a gametophyte. In mosses, after fertilization, the zygote grows into a sporophyte which consists of the foot, seta, and capsule.