<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 62-year-old man comes to the physician because of a 2-day history of fever, chills, and flank pain. Five days ago, he was catheterized for acute urinary retention. His temperature is 39.3C 102.7F. Physical examination shows right-sided costovertebral angle tenderness. Urine studies show numerous bacteria and WBC casts. Urine culture on blood agar grows mucoid, gray-white colonies. Urine culture on eosin methylene blue agar grows purple colonies with no metallic green sheen. Which of the following is the most likely causal pathogen?? A: Proteus mirabilis, B: Pseudomonas aeruginosa, C: Escherichia coli, D: Klebsiella pneumoniae, E: Staphylococcus saprophyticus,  <response>: Based on the information provided in the question stem, this 62-year-old man likely has a urinary tract infection that has progressed to pyelonephritis kidney infection given his fever, chills, flank pain, and costovertebral angle tenderness. The description of his urine studies showing bacteria and WBC casts confirms infection. The details about the urine culture growing mucoid, gray-white colonies on blood agar and purple colonies without metallic green sheen on EMB agar indicate the most likely pathogen is Klebsiella pneumoniae. D: Klebsiella pneumoniae 