The correct option is D All of the above
Mucoid connective tissue forms a compliant cushion around the vessels of the umbilical cord (where it is also called as Wharton's jelly). The tissue fills the space between the vessels and the simple squamous epithelium lining its surface. Mature connective tissue cell, chondrocyte is present in the umbilical cord. The extracellular component of embryonic tissue contains a sparse arrangement of reticular fibres and abundant ground substance.
Thus, the correct answer is option D.