The correct answer is (b). Yeast is a single-celled fungus that reproduces asexually through budding. Budding is a form of asexual reproduction in which a new individual grows out of a small protrusion on the body of the parent organism. The new individual eventually separates from the parent and becomes a new organism.
Amoeba is a single-celled organism that reproduces asexually through binary fission. Binary fission is a form of asexual reproduction in which the parent cell divides into two identical daughter cells.
Plasmodium is a protozoan parasite that causes malaria. Malaria is a disease that is transmitted to humans through the bite of infected mosquitoes. Plasmodium reproduces sexually in the human body and asexually in the mosquito body.
Leishmania is a protozoan parasite that causes leishmaniasis. Leishmaniasis is a disease that is transmitted to humans through the bite of infected sandflies. Leishmania reproduces asexually in the human body and sexually in the sandfly body.
In conclusion, the correct answer is (b). Yeast is a single-celled fungus that reproduces asexually through budding.