You can identify your customers by grouping them according to certain characteristics that you believe may be of importance to you. This is called demographics. This will help you not only know who your customers are, but also how you would be able to deal better with them. I hope this help if not just comment and I will get a notification to help again
Water act as an acid or base
If the scientists are studying the effects of different temperatures on the processing speed of a computer chip then they would need to know the temperature inside the computer.
However, your questions doesn't include the full question text, so I cannot be sure what answer you need.
If the question is what do they need to know to do this, the answer is C.
If the question is how could they measure this when they subject the computer to different temperatures, then the answer is D.
