The correct answer is option 2, Whale.

Option 1, Elephant, is the largest land mammal, but it is not the largest mammal overall. Elephants are known for their large size and can weigh up to several tons.

Option 2, Whale, is indeed the largest mammal. Specifically, the blue whale is the largest mammal ever known to have existed. It can reach lengths of up to 100 feet and weigh around 200 tons, making it even larger than the largest dinosaurs.

Option 3, Dinosaur, is not correct. Dinosaurs were reptiles, not mammals, and although some dinosaurs were huge in size, they were not the largest mammals.

Option 4, Rhinoceros, is also not correct. While rhinoceroses are large mammals, they are not the largest mammal. They can weigh up to around 5,500 pounds, but they are much smaller compared to whales.

In conclusion, the largest mammal is the whale, specifically the blue whale.