Explanation:

• Malaria is caused by Plasmodium (a protozoan). Malaria caused by Plasmodium falciparum is the most serious one and can even be fatal.
• 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, hemozoin, which is responsible for the chill and high fever recurring every three to four days.

Hence only statements 1&2 are correct.