Answer:
Option d. A solitary set of footprints in a track way
Step-by-step explanation:
This can be explained by the researches of Paleontologists who, after studying the fossils of dinosaurs found out the footprints of 3 tyrannosaurs evident of their hunting in packs which shows and also the footprints of birds and dinosaurs which includes both plant and flesh eaters in a track way are evident of the fact that dinosaurs were social creatures.