He needed to understand the concept of science to understand why it’s so important
Pretty sure it's basically saying to answer it for yourself and 3 other people. So for the tongue roll, on self, if you can roll your tongue say yes, for subject 1, ask another person, if they can say yes, if subject 2 (another person) can't, say no, and so on.
Answer:
the ability to produce clean water is an index of water quality based on six attributes