"Do you like the flavor of chocolate?" 味道 can also mean flavor.

"Do you like the flavor of chocolate?" should be acceptable.

"Do you like the flavor of chocolate?" Same as the above users ^

"Do you like the flavour of chocolate?"

Wish DuoLingo's matching was a bit smarter.

Same as the users below. Let's use the report button guys and gals, and let them know that our responses are valid translations.

You should also be allowed to put "enjoy"

taste = flavor = flavour

Do you like chocolate? Flavor is inherently implied in that short question. Only if you were asking something else (such as color) would there be any need of a qualifier.