A. I was told by somebody about the explosion in the Town Hall.
B. I was told about the explosion in the Town Hall.
C. I was informed that there was an explosion in the Town Hall.
D. I was told by somebody that there had been an explosion in the Town Hall.
Given sentence is in simple past tense and it is in active voice.
Rule :
Subject + (was / were) + V3 + Optional Agents.
