After determining the levels of calcium carbonate and the types of fossilized algae present in core samples taken from the bottom of Lake Titicaca in the Andes, a group of scientists was able to reconstruct the history of precipitation in tropical South America over the past 25,000 years.
A.the types of fossilized algae present in core samples taken from the bottom of Lake Titicaca in the Andes, a group of scientists was able
B.the types of fossilized algae that are present in core samples taken from the bottom of Lake Titicaca in the Andes, it was possible for a group of scientists C.the types of fossilized algae that had been present in core samples taken from the bottom of Lake Titicaca in the Andes, that made it possible for a group of scientists D.what types of fossilized algae had been present in core samples taken from the bottom of Lake Titicaca in the Andes, it was possible for a group of scientists E.what the types of fossilized algae were that were present in core samples taken from the bottom of Lake Titicaca in the Andes, a group of scientists was able正确答案A