Reports say that earlier this year, the suspect was taken to a hospital for medical treatment but remained in police ________.
本题考查近义词辨析。
题目意为“报道称，今年早些时候该嫌犯已被送往医院接受治疗，但仍在警方羁押之下。”A选项“宵禁，晚钟”，B选项“羁押，拘留”，C选项“挽留，延误”，D选项“保释”。police custody，意为警方羁押，B选项最符合题意。
故正确答案为B。