Answer:
An observational study.
Explanation:
Observational studies are those studies in which the researchers note the effects of risks factor, diagnostic test, or treatment without interrupting in it by changing anything. It is an investigative study that aims at distinguishing the effects caused by the treatment.
<u>In the given case, the researcher has used the observational study method to identify the effects of exercise on reducing the cholesterol level. He divided the people into two groups with 50 each. The research was performed without an awareness of these people as well as the technician measuring the cholesterol level. Thus it exemplifies an observational study</u>.
So, the correct answer is the observational study.
So with this equation, you have to work inside out with the parentheses. Firstly, solve 3+4: ![\{30-[12-7+2]*2\}-15](https://tex.z-dn.net/?f=%20%5C%7B30-%5B12-7%2B2%5D%2A2%5C%7D-15%20)
Next, solve 12 - 7 + 2: 
Next, solve 7 x 2, then 30 - that product: 
Lastly, solve 16 - 15, and your answer will be 1.
The correct answer are
Is there reliable evidence to support the reasons?
Are there logical reasons to believe the claim?
Is the author's claim clear to the reader?
Does the author's diction affect the reader as intended?