The passive voice is a grammatical "voice". The noun or noun phrase that would be the object of a corresponding active sentence (such as "Our troops defeated the enemy") appears as the subject of a sentence or clause in the passive voice ("The enemy was defeated by our troops").
So the answer would be:
<u><em>A hurricane watch has been issued by the authorities.</em></u>
The sight of the bus that travelled between her village and the nearest town, filled each time with a new set of passengers, was a source of unending joy for Valli.