Put the steps of endochondral ossification in the correct order. 1: formation of medullary cavity and appearance of secondary ossification centers 2: cavitation of hyaline cartilage within the cartilage model 3: invasion of internal cavities by periosteal bud and spongy bone formation 4: ossification of epiphyses; hyaline cartilage remains at epiphyseal plates and articular cartilages 5: formation of bone collar around hyaline cartilage model

The correct order is:

5: formation of bone collar around hyaline cartilage model  

2: cavitation of hyaline cartilage within the cartilage model  

3: invasion of internal cavities by periosteal bud and spongy bone formation  

1: formation of medullary cavity and appearance of secondary ossification centers  

4: ossification of epiphyses; hyaline cartilage remains at epiphyseal plates and articular cartilages  

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.