What is its primary advantage of multiple researches obtaining the same result

The primary advantage of multiple researchers obtaining the same result is that it makes the result of the researches more reliable, and the chances of a mistake are minimized.

If only one research is made, by a single person or team, on certain thing, the result of the research can not be seen as reliable. The reason for this is that the research has not been repeated numerous times, and the chances of a mistake are much higher, thus making the research not very trustworthy.

On the other hand, if multiple researches or teams of researches are doing a research on the same thing, and they do come to the same result, than we can say that the result is much more reliable. The reason for that is that multiple different people or teams have conducted multiple researches, and the result is always the same, thus meaning that is is reliable, and the chances of a mistake are much more minimized.

elements make up everything, and they combine to make compounds.

the answer is c