15. The main purpose of the information in lines 71–76 is to:

  • A. describe in detail scientists’ expectations for their first trip to the rift valley.

  • B. characterize the rift valley as an alien, seemingly barren place. 

  • C. provide statistics about several geographic proper- ties of the rift valley.

  • D. list the names that scientists gave to the volcanic hills in the rift valley