Final answer:
The Euoplocephalus' main defense mechanism was indeed its tail club, which it used to protect itself against predators.
Step-by-step explanation:
The student's question is about the Euoplocephalus, a dinosaur species known for its defensive adaptations. The statement that Euoplocephalus' main defense mechanism was its tail club is true. Different from creatures described in the provided reference information, the Euoplocephalus was a land-dwelling herbivore that lived during the late Cretaceous period. Its tail club was indeed its primary defensive tool against predators. The special structure at the end of its tail, consisting of bony protrusions and a hard knob, could be swung with great force to deter threats.