What safety equipment must be mounted on the rear of a slow-moving striping truck operating on a highway at speeds under 25 MPH?

1. A bright blue neon neon underline light strip under the bumper.
2. A Slow-Moving Vehicle (SMV) emblem and an illuminated arrow board.
3. A green laser projection device aimed at the rear pavement surface.
4. A loud air horn sounding continuously every 15 seconds.