Question

Who can question sahib's integrity?
Change into passive voice.

A detailed explanation is needed, providing 15 points for that.

Answer 1

By whom sahib's integrity can be questioned ? -is your answer
I can't explain like teachers but can only say that the active one was in present indifinite and in passive 'be' is used to suit the tense.
THANKS

Answer 2

Sahib's integrity can be questioned by whom ?

... because in passive voice the speaker or the doer isn't given more than the work or the main discription of the subject