Answer: d. is produced by secondary ossification centers.
Explanation: Basically after child birth, secondary ossification centers forms in the epiphysis. The epiphysis is the end of a long bone which is usually rounded.
The Ossification of the ends of long bones (epiphysis) is produced by the secondary ossification centers. The secondary ossification centers occurs after the occurrence of primary ossification. Most secondary ossification appears during the postnatal and adolescent age of a child. Arguably, most bones have more than one secondary ossification center.
