Answer:
Was found.
Step-by-step explanation:
In order to change an active voice into the passive voice, there are certain rules/rather ways of using the tenses and verbs. Active voices directly addresses the subject and object in their respective sentences, but in the passive voice, the sentence has to be reconstructed in such a way that the object comes first and then the subject is put in the end.
For example, supposing a sentence reads-
We found a bag of valuables on the road.
Here, the subject is 'WE' while the object is 'A BAG OF VALUABLES'.
Changing the above sentence in the passive voice, it will become-
A bag of valuables was found on the road by us.
The pronoun 'us' for the 'we' is at the end of the sentence while the object 'a bag of valuables' came to the fore of the sentence. Also, the verb structure changes from 'found' to 'was found'.
Thus, the verb that indicates the passive voice is "was found'.