D: ¿Te gusta vender los collares?
Gustar conjugated is still one word so it cannot be "gust a"
A verb ("vender") is singular so you cannot use "gustan"
A verb after gustar has to be infinitive
so the correct answer is ¿Te gusta vender los collares?
Literal Translation is "What day is the 27th of May" or to make it easier to understand "What day of the week is May 27th"
The answer would depend on the year.
Let's say the year is 2015. May 27th is on a Wednesday.
A possible response would be:
<span>"El día es el miércoles" which means "The day is Wednesday"
Hope this helped! :)</span>