The unicellular organism causing malaria-
(a) Amoeba
(b) Paramecium
(c) Euglena
(d) Plasmodium

Correct Answer: (d) Plasmodium

Explanation:

 Plasmodium, a microscopic and single-celled organism, is responsible for causing malaria. Female Anopheles mosquito is the carrier of Plasmodium and spreads malaria from one person to another. Plasmodium reproduces by the asexual method of reproduction known as multiple fission.