Descriptive investigations involve collecting data about a system, but not making what?

The correct answer to the following question will be "Tests or experiments".

Explanation:

Descriptive investigations attempt to build assumptions from either the predictions of the phenomena, even as experimentally investigated were mostly designed to allow the research scientist to make comparisons under various situations with both the control behavior.There are indeed enough that-called comparison investigations, that also gather information analyze varying environments but don't even include the regulate location.

So that the above would be the appropriate answer.

Hydrosphere is the correct answer