The theme of your story can be as broad as 'love' or 'loneliness' or as narrow as the idea that 'death is the unifying human experience'. It can also be a universal statement about humanity that an author investigates or explains through the course of a story.
Phlebotomy is where they make a puncture in a vein for the purpose of drawling blood so we can take out C. and then they aren't the ones analyzing it so we can take out B. too