Indicate Whether the Study Described Is an Observational Study or a Controlled

Multiple Choice

Indicate whether the study described is an observational study or a controlled experiment.
-A group of cancer patients is divided into two groups. One group is given a new drug to fight the side effects of chemotherapy and the other group is given a placebo. After three months they are asked to respond to a questionnaire about the frequency and severity of their side effects to see whether the new drug improved the overall negative side effects of chemotherapy.

A) Controlled experiment
B) Observational study