Question

What was the action of the state of Maryland?

seceded from the Union after Fort Sumter
did not secede from the Union
seceded from the Union after the election of Lincoln

Answer 1

did not secede from the Union

Maryland was a border state with strong Southern sympathies, but it never officially seceded. Federal measures (troop deployments, suspension of habeas corpus, arrests of secessionist leaders) and the need to keep Washington, D.C. secure kept Maryland in the Union.