The correct option is A early embryos
Unipolar neurons are only found in the early embryonic stages. They have a cell body with one axon only and no dendrites.
Olfactory epithelium and retina of the eye is made up of bipolar neurons. Bipolar neurons have a cell body with one axon and one dendrite. Spinal cord is made up of multipolar neurons which have a cell body with one axon and two or more dendrites.