What Was the "Three-Fifths Compromise

What was the "three-fifths compromise"?
A)The compromise over how many Senators each state would get.
B)The compromise that, for purposes of representation and taxation, made each "non-free person" (i.e. slave) count as three-fifths of a person.
C)The compromise between Hamilton and Madison that Hamilton would get to write three-fifths of the Federalist Papers.
D)The compromise on the number of soldiers each state would provide for the US military.
E)The compromise over the number of Senators required to overturn a presidential veto.