A pre-sales question means somebody is close. They have read enough to have one doubt left. How you answer decides the sale, and often several after it, because the exchange is public.
Answer the question asked
Not the one you wish they had asked. If they ask whether it supports two currencies, say yes or no first, then explain. An answer that opens with three paragraphs of context reads as evasion, and often is.
Say no clearly when it is no
"No, it handles one currency only" loses a sale you were never going to keep, and gains you a reputation with everyone else reading. A vague yes that turns out to be a no becomes a refund and a one-star review.
Speed matters more than length
A two-line answer in an hour beats a detailed one in three days. By day three they have bought something else. Set aside ten minutes a day for this rather than waiting for a moment when you can write properly.
Write it once, use it twice
If you have answered something twice, it belongs in the description. Your question list is a to-do list for your item page.
Remember who else is reading
Questions and answers sit on the item page. Every future buyer sees how you handle somebody who is unsure. A patient, specific answer is an advert; a curt one is a warning.
