Demetrius is a psychologist interested in the relationship between the ingestion of caffeine and how quickly people can respond to visual targets. Demetrius recruits a random sample of 200 participants for his study. He randomly assigns each participant to take a certain dose of caffeine, from 1 milligram to 400 milligrams. After the participants have taken their assigned dose of caffeine, they wait for 10 minutes, and then they undergo a test that measures their response time. In the test, after a random interval of time a star then appears on the screen and the participant is asked to press the spacebar as quickly as possible after the star appearsWhat type of methodology has Demetrius used in his study? A) correlational B) case study C) cross-sectional D) longitudinal E) experimental