Answer:
Option A, Neither the researchers nor the study participants know who is receiving the drug and who is receiving the placebo.
Explanation:
In a double blind test, both the researcher and research participants are unaware of the exercise in a medical test . During the research active medication is given to some of the research participants making sure that researcher is unaware of that while observing all the participants. However, at the end of the experiment ,both the researcher and research participants get to know who has received the treatment.
Hence, option A is correct
<span>The correct answer is b. ocean and freshwater system conditions generally remain constant throughout the year. This is not true because they are very different. For examples, freshwater rivers can completely freeze during the winter while oceans can't freeze completely, not even a bit. Also, the animals inside have completely different body structures to fight these changes.</span>
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