During the development of a new drug, which would be included in the study by the researcher to prevent any bias or unrealistic expectations of the new drug's usefulness?
a. a placebo
b. fda approval
c. informal consent
d. efficacy information

Option-A

Explanation:

In the given question, since the examiner has mentioned the time that the factor the researcher should include during the development of a new drug is "the placebo". A placebo is used during the experiment as control by and its effect depend on the expectations of the patient since the placebo does not contain the active drugs.

The FDA approval, informed consent and the information are not used until the study is going on.

Thus, Option-A is the correct answer.