Can someone help me with this problem please?

18. London scientists conducted a study to determine if chocolate can trigger migraines. Twelve migraine-prone subjects were given a peppermint-laced chocolate candy and eight migraine- prone subjects were given a peppermint-laced placebo made of carob, peppermint, and vegetable fat. Five subjects from the group given chocolate developed a migraine headache within one day. No one from the group given the placebo developed a migraine in the same time period. Source: Self magazine a. Which phase of the Scientific Method best describes this study? b. Is this an observational study or a controlled experiment? c. What is the response variable? d. What is the explanatory variable? e. Which group is the treatment group? f. Which group is the control group