The correct order of cell types from least differentiated to most differentiated is:
totipotent stem cells → pluripotent stem cells → multipotent stem cells → neuron
Totipotent stem cells can develop into any cell type, including extraembryonic tissues. Pluripotent stem cells can give rise to almost any cell type, but not extraembryonic tissues. Multipotent stem cells are more specialized and can form multiple cell types within a certain lineage. Finally, neurons are differentiated cells specialized for particular functions.
Therefore, the correct choice is:
totipotent stem cells → pluripotent stem cells → multipotent stem cells → neuron.