Nearly all mammals have seven cervical (neck) vertebrae. This fact implies that A. all mammals have to stretch their necks to obtain food. B. all animals can turn their heads the same amount. C. all mammals descended from a common ancestor.

The fact that nearly all mammals have seven cervical vertebrae implies that **C. all mammals descended from a common ancestor.** This suggests a shared anatomical trait that has been inherited from a common ancestor in the evolutionary lineage of mammals. The other options do not logically follow from the fact about cervical vertebrae.