The correct answer is the conference.
At the conference, Supreme Court justices meet and debate issues and discuss the cases before the Court.
The engraving done by Paul Revere represented the Boston Massacre. This was when four unarmed colonists were killed by members of the British army. This incident happened shortly after a series of taxes were put on the American colonists.
Paul Revere depicted this event in an engraving that shows the American colonists as being brutally murdered by the British army. In the engraving, all the British military members have guns while the colonists are standing their defenseless. This inflamed public opinion because it showed the British army as monsters who killed colonists without a cause.
To avoid bias, the historian must not rely on hearsays or opinions from different people because the facts could be misguided. He has to see the actual thing and create a neutral perspective focusing only on what is obvious. Therefore, the answer is letter A.