<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 56-year-old male comes to the physician because of a 2-month history of excessive sleepiness. He reports that he has been sleeping for an average of 10 to 12 hours at night and needs to take multiple naps during the day. Six months ago, he was diagnosed with small cell lung carcinoma and underwent prophylactic cranial irradiation. This patients symptoms are most likely caused by damage to which of the following structures?? A: Preoptic nucleus, B: Ventromedial nucleus, C: Suprachiasmatic nucleus, D: Supraoptic nucleus, E: Subthalamic nucleusn,  <response>: This is a clinical vignette describing a 56-year-old male with small cell lung cancer who underwent prophylactic cranial irradiation 6 months ago and now has excessive daytime sleepiness. The question asks to identify which brain structure is most likely damaged and causing his symptoms. Based on the history of cranial irradiation, we can narrow down the possibilities to structures in the brain that regulate sleepwake cycles when damaged. The choices given are all hypothalamic nuclei. The suprachiasmatic nucleus C is the primary circadian pacemaker and its damage would lead to disrupted sleepwake cycles. The other choices are less likely to be directly involved in regulating sleep.C: Suprachiasmatic nucleus 