The cranium is the name given to skull in medical terms because cranium is made of cranial bones that includes a cranial cavity surrounding human brain.
The other words such as spine (vertebral column) or zygote (formed after fertilization) do not depict the skull.
Thus, the options (b), (d) and (a) are incorrect.
The cranium is the name given to skull in medical terms because cranium is made of cranial bones that includes a cranial cavity surrounding human brain.
Therefore, the correct option is – c. Cranium