At birth, an infant's head is its body's size, whereas in adulthood, the head is its body's size. a. 1/4; 1/10 b. 1/3; 1/10 c. 1/3; 1/4 d. 1/4; 1/8

The correct answer is: d. 1/4; 1/8.

Baby's head must be large and must grow rapidly because its brain during the first 9 months of growth reaches half of its adult size. So, the head has to (compared to the size of their body) accommodate that brain. Sometimes it is even bigger than one-quarter of full baby’s length.