This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to brew gaiwan tea
Choose the best water.
Ninety nine percent of tea is water, so it's important to give some thought to the water you use for brewing. Tap water should be avoided since its chemical treatment imparts undesirable flavors and odors which interfere with the delicate aromatics of tea.

Options are:
(A). You may think it's wiser to use tropical-flavored water to, if possible, maintain culture quo. But for optimal taste, fresh quality water is even better.
(B). Don't taste water with its added bitterness. Although many people do think water is sweet, tea that is traditionally said to smell strong may be used as a practitioner's remedy.
(C). Various us water products include chlorine and iodine, from which to determine whether you want your water filtered. Add a little bit of the water.
(D). Home filters and other water purification systems can minimize and, in some cases, eliminate these problems. The best water for tea brewing is spring water with a natural mineral content that's neither too hard nor too soft.
The answer is:
(D).