Answer:
Malaria can be described as a disease which is caused by a parasitic organism. The Anopheles mosquito carries the parasite Plasmodium in it. When this mosquito bites a human being, the parasite gets transferred into the blood of the person causing malaria. Before entering the blood cells, the plasmodium travel to the liver where they get matured.
Malaria is a life-threatening disease which kills many humans each year, especially people living in underdeveloped countries.
I believe that the answer to your question would be A. Heart Begins.
A. Tetanus does not refer to the shape of a bacterium.
Answer:
The answer is:
B. Worms consuming the blood from mammals.
Algae isn't causing any harm to the sloth, rather its providing it with camouflage to hide from predators. Both creatures benefits since the algae gets to eat any parasites and other things in the sloths fur, plus they get a free ride and home in the process. The sloth isn't harmed and is helped by the algae since it provides camouflage (mutualism).
Tree frogs aren't causing harm to the trees since they are only using them to hide from predators, the tree serves as protection for the frogs and aren't harmed in the process (commensalism).
Two fish protecting each other from predators aren't harming each other in any way, rather they are protecting each other from another animal that wants to eat them (mutualism).
The worms however are harming the mammals because they are consuming the mammals blood, this is parasitism since one animal is benefiting and the other is harmed.
Hope this helps! :)