伤寒复发的原因是（）

A.再次感染伤寒杆菌

B.菌血症未完全清除

C.胆囊及肠道的伤寒杆菌侵入血流

D.潜伏在病灶或巨噬细胞内的伤寒杆菌再度繁殖入血

E.以上都不是

A 13-year-old visits the school nurse because he’s experiencing back pain, fatigue, and dyspnea. The nurse suspects that the child may have scoliosis. The nurse should first（）

A. send the child home to recover.

B. inspect the child for uneven shoulder height or uneven hip height.

C. arrange for the child to have spinal X-rays as soon as possible.

D. ask the child’s parent to take him to a physician immediately.