1. Do Nothing - Leave the missiles as they were. This would be unpopular amongst Americans.
2. An air strike - this would lead to war with Cuba and possibly with Russia with no assurance that the missiles would be destroyed.
3. Invade Cuba - This could lead to Russia invading West Berlin.
4. Attack Cuba and Russia with nuclear weapons.
5. Blockade Cuba - No Russian ships would be allowed access to Cuba. This was Kennedy's decision.