The correct option is (4).
Plasmodium parasites have a complex life cycle that includes three stages namely Gametocytes, Sporozoites and Merozoites.

1) Gametocytes/Stage 1

The male gametocytes called microgametocytes and female gametocytes called macrogametocytes are transmitted through an anopheles mosquito during a blood meal. The gametocytes within the mosquito develop into a sporozoite. The male and female gametocytes mate inside the gut of the mosquito, and after 15 to 18 days, they form a parasite called sporozoite.

2) Sporozoites/Stage 2

When the infected mosquito feeds on humans, the sporozoites are transmitted through the saliva into the bloodstream. After that, the sporozoites enter the liver cells and here they mature into schizonts. Later, these sporozoites rupture and release merozoites.

3) Merozoites/Stage 3

Over the next one or two weeks, each schizont multiplies in order to form several other forms known as merozoites. The merozoites exit from the lever, entering the bloodstream again and here they attack the red blood cells. The merozoites grow and multiply more while destroying all blood cells in that process. Certain merozoites develop into gametocytes, which are later ingested into the bloodstream by a mosquito and the whole cycle starts again.

So, when an infected female Anopheles mosquito bites, it inoculates sporozoites into the healthy human and takes up the gametocytes.

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