The loss of Numb in the Drosophila SOP lineage results in two IIa precursors and the production of extra hair and socket cells at the expense of neuron and sheath cells, while the overexpression of Numb results in extra neuron and sheath cells at the expense of hair and socket cells. Which cell type(s) does Notch activity specify?
A) IIa precursor B) Socket cell C) Neuron D) Both a and b E) Both a and c