【正确答案】 C

【答案解析】Urinary retention or incontinence may indicate cauda equina syndrome, which requires immediate surgery. An increase in pain on the second postoperative day is common because the long-acting local anesthetic, which may have been injected during surgery, will wear off. While paresthesia is common after surgery, progressive weakness or paralysis may indicate spinal nerve compression. A mild fever is also common after surgery but is considered significant only if it reaches 101°F(38.3℃).