THE TRAVELS OF MARCO POLO IN THE 12TH CENTURY _______ SO WELL KNOWN IF HE HADN’T WRITTEN THATBOOK WHILE IN PRISON

149. The travels of Marco Polo in the 12

th

century _______ so well known if he hadn’t written that

book while in prison.

A. must have been B. wouldn’t have been C. won’t have been D. could have been