Which of the following is the least likely physical sign of abuse?

The choice of bruises or scrapes on both knees and the palms as the least likely physical sign of abuse can be understood by considering the contexts in which such injuries typically occur. Bruises or scrapes on the knees and palms are common physical manifestations of accidental injuries, especially in active individuals or children who might fall during play or engage in physical activities. These types of injuries can arise naturally from everyday movement and do not inherently suggest intentional harm or abuse.

In contrast, the other options—such as bruises in unusual shapes, black eyes, facial scratches, or burns in unusual shapes—often indicate a form of trauma that is less consistent with common accidents. Unusual shapes could suggest non-accidental causes, as they do not conform to typical injury patterns seen from falls or general activities. This distinction is crucial in identifying possible signs of abuse, where injuries may present in ways that are inconsistent with typical accidents. Thus, bruises or scrapes on knees and palms are more often linked to benign incidents rather than abuse, making this the least likely sign of abuse among the options provided.