This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Axis is the name for: 
Select and explain. 
A. IV cervical vertebra, B. III cervical vertebra, C. II cervical vertebra, D. I cervical vertebra
C: II cervical vertebra
Answer: C: II cervical vertebra 
Explanation: Second cervical vertebra (axis)

Presence of odontoid process.
Transverse processes are small and lack the anterior tubercle.
Anterior margin of the inferior surface of the body projects downwards to a considerable extent.
Foramen transversarium is directed superolaterally (expand in typical vertebrae it is directed vertically)
Inferior surface presents a deep and wide inferior vertebral notch placed in front of the inferior articular process. The superior vertebral notch is shallow and is present behind the superior articular process.

Key concept:
Second cervical vertebra is called the axis. it is identiﬁed by the presence of the dens or odontoid process which is a strong, tooth-like process projecting upwards from the body. The dens is usually  believed to represent the centrum or body of the atlas which has fused with the centrum of the axis.