<s>[INST] context: Posture is regulated or acquired by reflex redistribution of tone in various muscle groups. Magnet reaction, also known as positive suppoing reaction, is seen in the spinal animal; Centre - Spinal cord Tonic neck reflex is seen in the decerebrate animal;Center - Vestibular nuclei. Neck righting reflex is seen in the midbrain or thalamic animal. Center - Midbrain nuclei/red nucleus. Optical righting reflex ~ When a person is falling, the surrounding objects will be seen tilted; and, from this visual input the upright posture will be retained. Center - Visual coex. Thus, intact coex is required for this reaction. Postural Reflexes and their centres Reflexes Integrated in Stretch reflex Positive suppoing reaction Negative suppoing reaction Spinal cord Tonic labyrinthine and tonic neck reflexes Medulla Righting reflexes (except optical righting reflexes) Labyrinthine righting reflexes Neck righting reflexes Body on head righting reflexes Body on body righting reflexes Midbrain Conditioned reflex Optical righting reflexes Hopping and placing reaction Coex [/INST] question: Which one of the following postural reflexes/reaction requires intact coex? | options: A: Tonic neck reflex B: Neck righting reflex C: Magnet reaction D: Optical righting reflex | answer: D </s>