Correct Answer: Liza is regarded as an expert by all of us.

Solution : The first option is the correct choice.

Passive voice is the voice in which the object experiences an action rather than the person who performs the action. Hence, the object in the active sentence becomes the subject in the passive voice.

The structure of the passive form in the case of the simple present tense is: "Singular object + is + past participle form of the main verb + prepositional phrase."

Therefore, the correct answer is: " Liza is regarded as an expert by all of us ."