Final answer:
Diplodocid bodies were long and relatively lightly built. They had distinctive shapes with long necks and tails, and their limbs were slender for their body size.
Step-by-step explanation:
The question is about the physical characteristics of dinosaurs that belong to the group known as diplodocids. The correct description of diploidocid bodies would be that they were long and relatively lightly built. Diplodocids, including well-known genera like Diplodocus and Apatosaurus, were famous for their distinctive body shapes with extremely elongated necks and tails, and relatively slender limbs compared to their overall body size. While they were large animals, their long and lean build made them one of the more lightly constructed groups of sauropod dinosaurs.