Final answer:
The spike or club at the end of the Stegosaurus' tail is called a Thagomizer.
Step-by-step explanation:
The correct answer is b. Thagomizer. The name "thagomizer" was coined by the cartoonist Gary Larson in a cartoon, and it has since been adopted by paleontologists. The thagomizer refers to the arrangement of spikes or plates at the end of a Stegosaurus' tail. These spikes were most likely used for defense against predators. The name given to the spike or club at the end of the Stegosaurus' tail is the Thagomizer. This term was coined after a comic strip by Gary Larson in his series 'The Far Side' where a group of cavemen refer to the tail spikes as a 'thagomizer' after a caveman named Thag who was killed by it. The use of this term has since been adopted in scientific circles and is used informally to describe the four to ten spikes found on the tails of stegosaurid dinosaurs.