Final answer:
Artemisinin is the antimalarial drug that increases ROS levels in target cells, thereby damaging the malaria parasite.
Step-by-step explanation:
The antimalarial drug thought to increase reactive oxygen species (ROS) levels in target cells is artemisinin. This compound, originally derived from a plant and discovered in the 1970s, acts as a prodrug that undergoes metabolism in target cells, producing ROS that are toxic to the malaria parasite. Other antimalarials like chloroquine, quinine, and mefloquine have different mechanisms of action and are not primarily associated with ROS production.