Q:Dolphins are interesting animals and researchers find them interesting to watch. They don't have hands, but can use tools to solve problems, just like us. Scientists have observed a dolphin trying to get a shy eel to come out of its hole by poking it with a dead fish. Many species of dolphin live in large societies. They have many different relationships and need a good communication system; they use a variety of sounds to communicate with each other. There is currently no evidence that dolphins have a language of their own. But scientists still have a lot to find out about these animals and so there are certain to be a few surprises in the future. At Kewalo Basin Marine Laboratory in Hawaii, the dolphin team have developed a sign langue to communicate with the dolphins, and the results are amazing. Not only do the dolphins understand the meaning of individual words, they also understand the significance of word order in a sentence. For example, when they were asked to 'touch the ball with your tail and then jump over it' they generally responded correctly and straight away, which showed that they understood the langue. Most mammals seem to enjoy play--but dolphins seems to like making their games as challenging as possible. On a beautiful day in 1997, researchers working at a beach, off the southern coast of Brazil, observed a little dog going into the sea and swimming towards the dolphins. To their surprise, the dolphins approached the dog and then started throwing it into the air. The dog seemed to enjoy the 'game' and continued playing with the dolphins for more than an hour. From then on, different dogs were seem trying to interact with the dolphins. Dolphins live in a very different world to ourselves, but they are very good at our 'intelligence tests'. For example, they will jump out of the water when they hear a whistle noise. They do this because they will get a fish as a reward. There is still much to learn about these flexible problem-solvers, but from the evidence so far, it would seem as though... When they play, dolphins seems to like making their games as _ as possible. A) difficult B) easy C) interesting D) relaxing
A:
A