I believe the answer to your question will be A)
The AV valves close first, then the semilunars open and close, then the AV valves open
Answer: d. double-blind
Explanation:
A double blind study can be define as the study in which both the researcher and participant do not know which participant is receiving a particular treatment. This method is useful as it prevents the bias in the results of the experiment.
The given situation is the example of double-blind study. Here, the participants as well as the researcher do not know which group of subject are receiving bacteria in the yogurt and which group is not receiving.
Answer:
they do not want to damage their lungs
Explanation:
