Wardha said to her sister, “How long do you intend to stay here?”

Wardha asked her sister that how long she intended to stay there.
Wardha asked to her sister how long she intended to stay here.
Wardha asked her sister how long she intended to stay here.

The correct answer is B. Wardha asked her sister how long she intended to stay there.

A is incorrect because it uses the word “that”, which is used to introduce a clause. In this case, the speaker is not introducing a clause, but is simply asking a question.

C is incorrect because it uses the preposition “to”. The preposition “to” is used to indicate a destination, but in this case, the speaker is not asking about a destination, but about a length of time.

D is the same as B, but with an unnecessary comma.