Bleaching of photopigment refers to:
Separation of retinal from opsin (B) is the right choice. This sits at the heart of Sensory System Eye Physiology: the wording points straight to what is happening in the tissue or organ system. A useful study habit is to ask what the structure or process is for: this is mainly a definition check, and Separation of retinal from opsin is the standard term or meaning used in Sensory System Eye Physiology. That reasoning supports Separation of retinal from opsin. One solid sentence about why this works is enough for recall — you do not need a long essay for every MCQ.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.