Question

read the passage. until the late 1800s, people believed that malaria, a common tropical disease, was caused by breathing \bad air.\ then doctors identified a microscopic parasite in the blood of malaria patients. but how did the parasite enter the body? some doctors suspected that insects transmitted the parasite, but they lacked empirical evidence until ronald ross, a british physician, began conducting experiments with mosquitoes. ross discovered that these tiny pests were responsible for shuttling the parasite from one infected person to the next. if people in tropical environments could avoid mosquito bites, they could also avoid getting malaria. what is the meaning of empirical as used in the passage? relating to spiders and insects based on scientific observation basic or of central importance involving the cure to sickness

Explanation:

The passage states doctors suspected insect transmission but lacked "empirical evidence" until Ross conducted experiments. "Empirical" here relates to evidence from scientific observation/experiments.

Answer:

based on scientific observation