According to the paragraph 8, what does the author conclude about the intelligence of cetaceans? A. It is not appropriate to judge cetacean intelligence in human terms. B. Cetaceans probably possess a mental sophistication that is as complex as that of humans. C. Although cetaceans may appear to be intelligent, they have fewer problem-solving skills than most animals. D. Their ability to learn American Sign Language indicates that cetaceans have a high level of intelligence.