Ouch! You step on a tack and ran away without even thinking. Then you decide to pick up the tack and place it back in a desk drawer. Which body system does that involve?
I'd argue the nervous system because you sense pain through your nerves and when you realize something is poking you bam your nerves recognize it and tell your brain "UH OH CHEIF THERE'S A TACK" and you pull it out.
