Cold-blooded animals, also known as ectothermic animals, are organisms that rely on external sources to regulate their body temperature. They do not have the ability to internally regulate their body temperature like warm-blooded animals do.

In this question, the correct answer is option-2, Shark. Sharks are cold-blooded animals. They belong to a group of fish called Chondrichthyes, which also includes rays and skates. These animals have a cartilaginous skeleton, large livers, and a unique system of blood vessels called a "rete mirabile" that helps regulate their body temperature.

Option-1, Dolphin, and option-4, Porpoise, are warm-blooded animals. They belong to a group of mammals called cetaceans. Dolphins and porpoises have a thick layer of blubber that helps them maintain their body temperature in cold waters.

Option-3, Whale, is also a warm-blooded animal. Whales are the largest mammals on Earth and have adaptations such as a thick layer of blubber and a large body size, which help them retain heat.

To summarize, out of the given options, only option-2, Shark, is a cold-blooded animal. Dolphins, porpoises, and whales