When a sentence has a "People thought that..." structure, the passive can be formed in two ways. One is "The despot was thought to be corrupt", and the other is "It was thought that...". However, the former is more idiomatic in English tests.

১. Option (খ) is also grammatically correct, but (গ) is the preferred complex-to-simple passive transformation.
২. Option (ক) is wrong because it uses "had been" instead of "was".
৩. Option (ঘ) uses the present tense "is", which doesn't match the original past tense "thought".

অতিরিক্ত তথ্য: Passive voice is used when the focus is on the person or thing affected by the action.