I would say the correct answer is that has an undetermined answer.
If a subject has been thoroughly covered, then there is no need for this researcher to do it all over again. If it's impossible to answer, there is no need to try. If it can be answered easily, then it doesn't really require a research. This leaves us with the last option, because a researcher might want to try and determine the answer.
The reader has to keep very careful track of the character
Please show answer options
In one study people who walked 15 minutes a day lost an average of two pounds per month is the answer
<span>Two weeks later, Dr. Jekyll gives a small dinner party, for which, we gather, he is well known, for the narrator refers to it as being "one of his pleasant dinners." Five or six of Dr. Jekyll's old cronies are invited, and among them is Mr. Utterson. As usual, the food is superb, the wine good, and Utterson manages to be the last guest to leave.</span>