Which of the following is a six-point violation in Ohio?

Answer: C — Leaving the scene of a collision (hit and run)

A six-point violation in Ohio carries the most severe penalties, and the only option that fits this criteria is leaving the scene of a collision (hit and run). Failure to yield, all speeding offenses, and driving without a license are considered minor violations and do not carry six points. Additionally, leaving the scene of a collision is a serious offense as it can result in injury or property damage, while the other options do not necessarily pose the same level of danger.