They were deciding whether to create a naval blockade, because the Cubans were traveling mostly by ocean, or they wanted to do a military strike. They could not decide of which would have been the most efficient way to attack the Cubans.
The best and most correct answer is After discovering what they thought was a threat in Cuba, Kennedy’s team debated whether to "establish a naval blockade or create a hotline." This was part of the major sequence of events during the Cuban Missile Crisis.
