Which statement describes the difference between wet-pipe and dry-pipe sprinkler systems?

• A. Wet-pipe systems have water-filled piping; dry-pipe systems have pressurized air until heads are activated.
• B. Both have water-filled piping; the difference is temperature rating.
• C. Wet-pipe systems use foam; dry-pipe uses dry chemical.
• D. Wet-pipe is for residential; dry-pipe for industrial only.

Answer: (A)