Under what condition may a property possessor be strictly liable for injuries inflicted by their animals against a trespasser?

A property possessor may be held strictly liable for injuries inflicted by their animals against a trespasser primarily when the animal in question is deemed to be dangerous or has a propensity to cause harm, such as a vicious watchdog. This rule is grounded in the principle that if a property owner maintains an inherently dangerous animal, they assume the risk that such an animal could harm someone, regardless of whether that person is a trespasser or not.

In the case of a vicious watchdog, the nature of the animal implies an increased risk of harm, which the property possessor must manage. The law thus holds the property owner liable for injuries caused by such an animal, recognizing that the presence of a known dangerous animal creates a liability that extends beyond the typical defenses applicable to trespassing.

When considering the other options:

A highlights child trespassers but does not independently answer the requirement of strict liability in this context. C indicates a situation where the trespasser is invited, which would not apply to strict liability for trespassers. D mentions prior knowledge of trespassing, but strictly speaking, knowledge alone doesn’t establish liability in the context of injuries from animals; rather, it is the animal's nature that plays a pivotal role in this legal framework.