The correct option is C Algae
Syngamy is the process of fusion of gametes leading to the formation of a diploid single celled zygote.
Mosses are plants belonging to the division Bryophyta in which the male and female reproductive organs, antheridia and archegonia respectively, are present on the gametophytic plant body. The male gametes or antherozoids are motile and are carried via water to the archegonia where fusion of the male and female gametes occur. Thus the process of syngamy occurs within the body of the organism.
In algal life forms the motile gametes are released into water at the same time and they fuse in water to give rise to diploid zygotes. Thus, syngamy occurs outside the body of the organisms.
Ferns are pteridophytes which have a gametophyte prothallus containing male and female reproductive organs, antheridia and archegonia respectively. The male gametes or antherozoids are motile and are carried via water to the archegonia where fusion of the male and female gametes occur. Thus the process of syngamy occurs within the body of the organism.
For most higher forms of fungi, the fertilisation is internal as the male gamete is transferred from the antheridium to the oogonium of the fungus where fertilisation occurs.
(B) Algae