An agreement to count slaves as three- fifths of a person was related to the way in which population would be counted in each state. For the given question, the correct option is option āCā. During the Constitutional convention in the year 1787 in United States the Three-Fifths Compromise was agreed upon by the delegates of the northern states and the southern states. This was a result reached after debating over the counting of the number of slaves in case of taxing people and also for representation in the Legislative assembly.