Question

long bone
epiphysis
articular cartilage
ephiphyseal line
spongy bone
diaphysis
medullary cavity
nutrient foramen
endosteum
periosteum
articular cartilage
epiphysis
bones grow in diameter due to bone formation
a beneath the periosteum.
b within the metaphysis.
c in the medullary cavity.
d in the epiphyseal plate.

Explanation:

Bone growth in diameter occurs through appositional growth. The periosteum has osteoblasts that deposit new bone matrix on the outer surface of the bone. This process leads to an increase in the bone's diameter. The metaphysis (related to longitudinal growth), medullary cavity (contains bone marrow), and epiphyseal plate (for longitudinal growth in children) are not the sites for diameter - related bone formation.

Answer:

A. beneath the periosteum.