In 1850 …………………… established one of the first detective agencies in theUnited States.

In 1850 …………………… established one of the first detective agencies in theUnited States.

A. it was detectivePinkerton

B. detective Pinkerton 

C. detective Pinkerton who

D. when detectivePinkerton

Câu trả lời là: B là đáp án đúng