Have you ever ______ Dhaka

The correct answer is "been to".

So, the sentence would be: "Have you ever been to Dhaka?"

Explanation:

• "Been to" is the correct phrase to indicate visiting a place in the past (it suggests movement to the place).
• "Been on" typically refers to being on a journey or a particular type of trip (e.g., "been on a cruise").
• "Went to" and "Went on" are both past tense forms, but they do not work in this case because the sentence is in the present perfect tense ("Have you ever..."). The present perfect tense requires "been" with "to".

So, the sentence using "been to" is grammatically correct.