When must a road collision be reported?

A road collision must be reported when there is injury caused to any animal not being carried in a vehicle. This requirement underscores the responsibility of drivers to not only account for human safety in the event of a collision but also to consider the welfare of animals affected by such incidents. It reinforces the legal expectation that drivers report collisions that have wider impacts, which can include injuries to animals, highlighting the importance of animal welfare in traffic-related events.

The other scenarios mentioned in the options are less comprehensive in terms of what necessitates reporting. For instance, simply having property damage without injuries or considering only the damage to one's vehicle does not fulfill the legal obligation to report the incident under certain circumstances. Moreover, failing to report a collision when no one is injured would overlook potential legal or procedural requirements that might still mandate a report, especially if there are other factors at play, such as environmental impacts or injuries to animals involved.