Concept:The sentence is in passive voice, so the subject ("the meeting") receives the action and a form of "to be" must precede the past participle.
Explanation:In passive voice, the structure is "subject + is/am/are/was/were + past participle".
The meeting did not perform the action of adjourning; the Chairman did.
Therefore, part (a) should read "was adjourned", not just "adjourned".
Part (b) "by the Chairman" correctly shows the doer of the action.
Part (c) "after about three hours of deliberation" is a correct prepositional phrase.
The error lies only in part (a).
The correct sentence is: "The meeting was adjourned abruptly by the Chairman after about three hours of deliberation."
Answer:A