Apsychiatrist studying the affects of healthy eating habits on mood improvement. he identifies 25 people who eat healthy food and 25 who do not. each other 50 people is given a questionnaire design to determine their mood. none of the 50 people participated in the study knew they were part of the study. which statement is true? a this is a random mise comparative experiment be this is a double blind study see this is an observational study d this is matched pairs design

The statement which is true is:

B. This is a double blind study

Step-by-step explanation:

Double Blind Study is such a study method in which participants don't know about the information that can effect the participants in order to eliminate the bias. This is the case with out situation in which participants didn't know that they were the part of a study.  Randomized Comparative Experiment is such an experiment in which participants are randomly selected for different treatments as well as the comparison of effects of different treatments is done. So, the option A is not valid in our situation.Observational Study is such a study in which we only observe the the data collected or participants. We observe the cause-effect relationship in this study. Matched Pair Design is such an experiment in which subjects are grouped in pairs. It is a special type of randomized block design.