The infective stage of malarial parasite, Plasmodium is:

Sporozoite

The correct answer is Option (3) → Sporozoite 

Plasmodium enters the human body as sporozoites (infectious form) through the bite of infected female Anopheles mosquito. The parasites initially multiply within the liver cells and then attack the red blood cells (RBCs) resulting in their rupture. The rupture of RBCs is associated with release of a toxic substance, haemozoin, which is responsible for the chill and high fever recurring every three to four days.

When a female Anopheles mosquito bites an infected person, these parasites enter the mosquito’s body and undergo further development.

The parasites multiply within them to form sporozoites that are stored in their salivary glands. When these mosquitoes bite a human, the sporozoites are introduced into his/ her body. It is interesting to note that the malarial parasite requires two hosts – human and mosquitoes – to complete its life cycle. The female Anopheles mosquito is the vector (transmitting agent) too.

                                               Stages in the life cycle of Plasmodium