(a) : Plasmodium has two hosts. (i) Female Anopheles mosquito: Here the sexual phase of the malarial parasite occurs and it is considered the definitive host of malarial parasite. (ii) Human beings : Here the asexual phase of malarial parasite occurs. It is considered as the intermediate host. Options (b), (c) and (d) are the stages of the asexual phase of Plasmodium.