关于一条GRE的填空题,(i)_____ it has fallen from popularity,legends o

关于一条GRE的填空题,
(i)_____ it has fallen from popularity,legends of the kingdom of the priest-king Prester John stirred the imagination of Europe for the second half of the Middle Ages (and beyond),when countless explorers and cartographers traveled to the East,hoping to (ii)_____ the true kingdom's location and learn more about its leader.
Blank(i) Blank(ii)
A Before D contravene
B Given that E descry
C Although F debunk
主要是第二空,EF 之间选哪一个呢?