Final answer:
The correct answer is C- It had hard parts. Trilobites from the Cambrian period are distinguished by their hard, mineralized exoskeletons, which set them apart from many of the earlier, soft-bodied organisms.
Step-by-step explanation:
The trilobite fossil from the Cambrian period is characterized by several distinctive features that set it apart from organisms that lived earlier in time. Among the options given, the correct answer is C- It had hard parts. This is what distinguished trilobites from many of the earlier, mostly soft-bodied organisms. The Cambrian period marks a significant point in the history of life on Earth known as the Cambrian explosion, where there was a rapid increase in the diversity of life, with many new kinds of organisms evolving. Trilobites, being small ocean invertebrates and part of the arthropod group, were very abundant during this time and were among the early animals to develop hard, mineralized exoskeletons, which contributed to their success and to their fossil record.