Dolphins are smaller whales, with a total of 62 species, distributed in all oceans in the world. Dolphins are generally 1.2 to 10 meters in length and 45 to 9,000 kg in weight. They mainly feed on small fish, squid, shrimp, and crab. They like to discuss "Collective" life, ranging from a few to a few hundred. Dolphins are a superb and intelligent marine mammal. Based on the above statement, which of the following conclusions can be drawn? ? ['Dolphin is a smaller mammal.', 'Some clever mammals live in the sea.', 'At least 62 types of mammals in the ocean.', 'Dolphins are empathetic and can imitate human actions.']