Which one of the following is categorised as a parasite

1. The female Anopheles bites and sucks blood from humans
2. Human foetus developing inside the uterus draws nourishment from the mother
3. Head louse living on the human scalp as well as laying eggs on human hair
4. The cuckoo (koel) lays its eggs in crow’s nest.

Head louse is an obligate ectoparasite of human scalp and as well as laying egg on human hair.