Final answer:
Guardrails, Rumble Strips, and Changeable Message Signs are all highway safety features.
Step-by-step explanation:
Guardrails and Rumble Strips are both examples of highway safety features. Guardrails are barriers placed along the edge of the road to prevent vehicles from running off the roadway, while Rumble Strips are raised or grooved patterns on the road surface that create audible and tactile vibrations to alert drivers if they are drifting out of their lane. Changeable Message Signs can also be considered a highway safety feature, as they display important information to drivers in real-time, such as traffic conditions or road hazards.