A 7-year-old boy is evaluated for short stature. His height is at the 3rd percentile for age, and radiographs show delayed epiphyseal closure in long bones. Serum growth hormone, insulin-like growth factor-1, and thyroid function tests are all normal. On physical examination, there is no evidence of skeletal dysplasia or metabolic disease. A knee radiograph is obtained for skeletal age assessment and shows a thickened growth plate with preserved architecture and expanded zones of cartilage extending toward the metaphysis. Which of the following histologic zones of the growth plate is the primary site where cartilage cells enlarge and accumulate matrix before undergoing ossification to drive longitudinal bone growth?

1. A)Resting (germinal) zone, where quiescent chondrocytes provide the stem cell pool for continuous growth
2. B)Proliferative zone, where rapid mitotic division of flattened chondrocytes increases cell number
3. C)Hypertrophic zone, where chondrocytes enlarge and the extracellular matrix becomes calcified before bone depositionGABARITO
4. D)Zone of calcification, where mineral is deposited in the longitudinal septa between enlarged chondrocytes
5. E)Zone of ossification, where osteoblasts replace calcified cartilage with woven bone