Which of the following best describes a properly controlled experiment

example data ,

Explanation:

is The scientific procedure ander taken to make discovery test a hypothesis or demonstrate a known fact

economic impact of malaria is estimated to cost africa $12 billion every year. this figure factors in costs of health care, absenteeism, days lost in education, decreased productivity due to brain damage from cerebral malaria, and loss of investment and tourism.

trachea, alveoli, lung capillaries, arteries