In earthworm , Photoreceptors are located in
Prostomium
Ventral dermis
Dorsal dermis
Both (a) and (c).
As we learned
Photoreceptors in earthworm -
In earthworm, photoreceptors are located in prostomium and dorsal epidemis. They preceive light intensity with help of phaosomes (optic organalles)
-