Answer :
Fort Sumter ; on April 12 1861 confederate guns fired on port Sumter in the habor of Charleston, south Carolina and the Civil war began. Confederate told Robert (commander of the port) to surrender the port of face an attack, there was no enough supplies and he needed help thus he told a desperate message to Lincoln. In the question Lincoln's response to the port of Sumter was that he called 75000 volunteers to serve for 90 days in order to put down the rebellion after the fall of fort of Sumter. Therefore the correct answer is A
The answer would be A. After the Battle of Fort Sumter, Lincoln then called for 75,000 volunteer soldiers who would serve for 3 months to increase the scale of the rebellion. His request was met with varied responses from the states.