In an observational study, researchers try not to:
O
O
O
A. influence the people in the study.
B. include people who are difficult to contact.
c. ask questions that are too obvious.
O
D. photograph any of the subjects.

I would say that  C researchers try not to ask questions that are too obvious. Because if the question is obvious, then I would think there would be no reason to research it. But I don't know fore sure. I hope this helps you! :)

Explanation:

both the house and senate must approve the conference report.   after it is approved by both on an identical from, it will be sent to the president.   if the president approves it, it will become law.

jupiter is mainly composed of hydrogen and helium just like a star. spectral analysis of jupiter has revealed that in addition to hydrogen and helium, the planet is made of water, methane and ammonia. those elements are in trace amounts. the core of the planet is thought to contain some rock and metallic hydrogen. i hope this will give you the answer to your question! : d