If One Were to Transplant Olfactory Neurons and Their Ensheathing

If one were to transplant olfactory neurons and their ensheathing glial cells at the lesion site in a spinal cord injury, full recovery would likely still not occur because

A) the spinal cord histology is too dissimilar to that of the olfactory bulb.
B) different intracellular signaling pathways exist in the olfactory bulb as opposed to that of the spinal cord.
C) olfactory neurons are too fragile for such transplant procedures.
D) olfactory neuron re-growth in their new environment lasts for only a short time.
E) ensheathing glial cells die off almost immediately upon being transplanted into their new spinal cord environment, because the latter has too many inhibitory factors associated with large amounts of myelin.