<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 34-year-old woman comes to the fertility clinic with her husband for infertility treatment. The couple has been having unprotected intercourse for the past 2 years without any pregnancies. This is their first time seeking fertility treatment. The patients past medical history includes asthma. She denies any menstrual irregularities, menstrual pain, abnormal bleeding or past sexually transmitted infections. The husband reports that he would get sick easily and would always have some upper respiratory infections. Physical examination of the wife demonstrates nasal polyps bilaterally; vaginal examination is unremarkable. Physical examination of the husband is unremarkable. Semen analysis results are shown below:Semen analysis:Volume: 1.9 mL Normal 1.5 mLpH: 7.4 Normal: 7.2Sperm concentration: 0 milmL Normal: 15 milmLTotal sperm count: 0 milmL Normal: 39 milmLTotal motility: NA Normal: 40Morphology: NA Normal: 4 normal formsWhat is the most likely explanation for this couples infertility?? A: Deletion of Phe508 in husband, B: Deletion of Phe508 in wife, C: Undescended testes in husband, D: XO chromosome in wife, E: XXY chromosome in husband,  <response>: Based on the information provided in the question stem, the key findings are:- The couple has been trying to conceive for 2 years without success, indicating infertility. - The wife has a history of asthma and nasal polyps, but otherwise normal fertility workup.- The husband reports frequent upper respiratory infections and has azoospermia no sperm on semen analysis.The husbands azoospermia in the setting of frequent respiratory infections points to a genetic disorder like cystic fibrosis as the most likely cause of his infertility. Cystic fibrosis is associated with congenital bilateral absence of the vas deferens CBAVD, which prevents sperm transport and leads to azoospermia. The most common genetic mutation causing cystic fibrosis is deletion of Phe508.Therefore, the most likely explanation for this couples infertility is deletion of Phe508 in the husband, leading to CBAVD and azoospermia.A: Deletion of Phe508 in husband 