"As you reach for a rose, you unexpectedly feel the painful poke of a thorn. You quickly withdraw your hand. Which part of this process is accomplished mainly by the central nervous system

Withdrawing your hand is accomplished by your nervous system.

Explanation: when the thorn pokes you, the pain receptors send messages to your brain or signals telling you to remove your finger.

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.