Final answer:
Option (a), Longitudinal bone growth in females typically continues until around the age of 18, when the epiphyseal plates close and bone growth in length ceases.
Step-by-step explanation:
On average, longitudinal bone growth in females continues to about 18 years of age. This is due to a process known as epiphyseal plate closure, where cartilage cells stop dividing, and cartilage is fully replaced by bone. As a result, the growth plates, known as epiphyseal plates, fade, leaving behind an epiphyseal line or remnant, which signifies the fusion of the epiphysis and diaphysis, marking the end of bone lengthening.