Which is the correct example of a trace fossil?

A trace fossil is a fossil that is not a direct impression of the organism itself, but rather a record of an organism's activity or movement. Footprints, trackways, burrows, and other types of impressions are examples of this. Footprints are one of the most common and well-known types of trace fossils, as they reveal information about ancient organisms' movement and behaviour, including the size and shape of their feet.

These fossils can reveal details about the anatomy, biology, and evolution of a wide variety of species, including humans, other mammals, birds, reptiles, and even dinosaurs.

The remaining options are not trace fossils. "Petrified wood" is a type of body fossil formed over time when the original organic material of wood is replaced by minerals. Body fossils include "tooth" and "hardened bone," which provide direct evidence of an organism's physical structure.