a lot of historians believe the battle of fort sumter was the start of the war, as it was the first official battle. however, there were zero casualties.
a lot of other people believe when lincoln was elected was the start, because that event led many southern states to secede very quickly.
b. the president signs a bill into a law
i believe this is the correct answer through some reading and research also the words limit and execute kinda tripped me up ill let you know if i find a better answer.
hiring a substitute so a is the answer.