Because a rockslide had blocked much of the passage, the spelunking team was not able of exploring the full extent of the cave.

A. the spelunking team was not able of exploring the full extent of

B. the full extent was not able to be explored by the spelunking team of

C. the spelunking team was unable in exploring, to its full extent,

D. therefore the spelunking team was unable to explore the full extent of

E. the spelunking team was unable to explore the full extent of