Question: To make a piping tip from a soda bottle,

  Options: 
 A. screw on the cap, cut a star shape into the cap with an X-acto knife, and then slice off the top of the bottle 1" from the end with the knife.
 B. screw on the cap, cut a star shape into the cap with a serrated knife, and then slice off the top of the bottle 1" from the end with the knife.
Answer: A