Answer
C
Work Step by Step
Option A is incorrect. The backbone appeared after lampreys appeared; therefore, lampreys do not have this characteristic.
Option B is incorrect. Four limbs appeared after the notochord appeared, not before.
Option D is incorrect. The placenta appeared after mammary glands appeared.
Option C is correct. Humans and lampreys shared a common ancestor because the two branches arose from a single broader clade.
