The correct option is C.
Roundworm belongs to the kingdom animalia and to the phylum nematoda. It has round, unsegmented, smooth and thin body which can grow to the maximum of four feet in length. It has a bilateral symmetry. A roundworm has no skeleton and it reproduces sexually.
Malaria is spread by mosquitoes because females pick up a parasite and when they bite someone to nurture their eggs it spreads
Natural selection can cause speciation, which increases the biodiversity of an ecosystem. Several bacterial colonies are placed on a petri dish that contains agar with antibiotics. After 24 hours, ninety percent of the original bacteria die, but the remaining ten percent survive and later reproduce.