As compared to whole body, the head of new born human baby is
A new born's head is very large in proportion to the body, and the cranium is enormous relative to his or her face. the new born's is about ¼. Normal head circumference for a full-term infant is 33–36 cm at birth. At birth, many regions of the new born's skull have not yet been converted to bone, leaving "soft spots" known as fontanels. It undergoes many changes. Due to this, the adult human skull is about one seventh of the total body length,
So, the correct option is ‘one – fourth’.