(a) If a school bus is not equipped with an electronic warning device as defined under § 6-19-125, a school district may have printed or otherwise displayed on the exterior of a school bus between the two (2) windows of the rear emergency exit door on a Type C bus or immediately below the rear emergency exit window on a Type D bus the following notification:
"ARKANSAS LAW: STOP WHEN RED LIGHTS ARE FLASHING".
(b) A school bus that is purchased on or after January 1, 2011, shall be equipped with either:
(1) A notice printed or otherwise displayed as provided under subsection (a) of this section; or
(2) An electronic warning device as defined under § 6-19-125.