Dont quote me on this but i believe the answer is c
I belive it is the civil war
Answer
H.R. signifies a House bill and S signifies a Senate bill.
Explanation
H.R is House Resolution. A Joint Resolution is a legislative proposal that requires the approval of both Chambers in identical form and the president's signature to become law.
A bill is proposed legislation under consideration by a legislature.A bill does not become law until it is passed by the legislature and, in most cases, approved by the executive. Once a bill has been enacted into law, it is called an act of the legislature, or a statute.
He Washington Naval Conference, also named the Washington Arms Conference or the Washington Disarmament Conference