Answer : 2. "Did you leave your bag in the bus?"
Explanation :

The given sentence is in a passive voice form, hence we need to convert it into an active voice form.
We need to follow these instructions while changing the voice of an interrogative sentence.
The inverted form of the verb i.e. Did you leave, will commence the sentence.
The given sentence is in the simple past tense.
The active voice form for the simple past interrogative sentence:
Helping verb (Did) + subject + V1 + object? At last line up the remaining part.
Following these steps, we finally get- Did you leave your bag in the bus?