GOLD ________ NEAR SAN FRANCISCO IN 1848, AND THE GOLD RUSH STARTED...

29. - TRAC NGHIEM ON THI TOT NGHIEDE CHNH SUA
TRAC NGHIEM ON THI TOT NGHIEDE CHNH SUA

29.

Gold ________ near San Francisco in 1848, and the gold rush started the following year.

A. discovered

B. was discovered

C. has been discovered

D. is discovered