Critical Reasoning: Investigation Questions

To which Critical Reasoning question type does the following question stem belong?

"Which of the following would it be most useful to know in order to evaluate the researcher's hypothesis?"

Conclusion Weakening questions ask us to weaken the argument's conclusion, so they include either the word weaken or a synonym of weaken - undermine, cast doubt, call into question. 

Good!

Investigation questions ask you to point out the factor which is most significant in determining whether the conclusion is valid. You can identify them by the words investigation, evaluation, or useful.

Argument Flaw questions ask us to find a flaw in the argument/conclusion. This question, on the other hand, is neutral about the conclusion. We're asked for information that will help evaluate the conclusion (hypothesis), not show its absurdity.  

Conclusion Strengthening questions ask us to strengthen the argument's conclusion, so they include either the word strengthen or a synonym of strengthen - supports.