Is this dorsal or ventral??

Dear student

Option 4 is correct.
Earhtworm has photoreceptors on dorsal surface. A photoreceptor is a single cell with ovoid shape having a nucleus and clear cytoplasm which  contains a network of neurofibrillae and a small, transparent L-shaped lens or optic organelle. The function of lens is to focus light rays from all directions on the neurofibrils. The are more numerous on the prostomium and first segment.

Regards.