People have long known that elephants are extremely intelligent and very social creatures. But many scientists remained doubtful that the animals could solve particularly complex tasks. Researchers in Thailand performed an experiment to test elephants’ ability to work together. To access a food reward, two elephants had to pull each end of a rope at the same time. If they pulled only one end, the rope would come to them, but the food would not. Six pairs of elephants were tested 40 times over two days, and every pair discovered how to acquire the food.
The elephants demonstrated ________.
A aggressiveness
B cooperation
C indignation
D obedience