"Đó là một sự lựa chọn đúng."

Translation: That is a correct choice.

[LostinVN]

This sounds weird in English. If it's the right one and it is a choice then we can assume there is only one right choice. Therefore we say: that is the right choice NOT that is a right choice.
Can you give me an example of when to would have more than one correct choice?

[wordgeek416]

How about a multiple-choice test where more than one choice may be correct?

[Johnathan363023]

Even in multiple choice tests there are only ever 1 correct answer, you may need to select many options but unless everything is selected it is not the correct choice.

If this phrase is indeed meant to be used in such a crippling way as you insist then DL needs to make it clear.

[Johnathan363023]

Agreed, it should be the correct choice.

[WonderWoma23572]

The hints say "right". Please accept. Right sounds more natural in English.