Option 1: Dolphin - Dolphins belong to the mammal group and share many similarities with humans. Both humans and dolphins are warm-blooded, have lungs for breathing, and nurse their young with milk. Dolphins also display high intelligence, social behavior, and advanced communication skills, which are traits associated with higher evolution. Therefore, from an evolutionary point of view, dolphins can be considered closer to humans.

Option 2: Flying fish - Flying fish belong to the group of ray-finned fishes and are not closely related to humans in terms of evolutionary lineage. While they have adapted to glide above water for short distances, they do not possess characteristics that are indicative of a close evolutionary relationship with humans.

Option 3: Shark - Sharks belong to the group of cartilaginous fishes and have a completely different set of traits from humans. They have no lungs and rely on gills for breathing. Sharks also lack higher cognitive abilities and social behaviors associated with mammals like dolphins and humans.

Option 4: Tortoise - Tortoises belong to the group of reptiles and have even fewer similarities with humans compared to dolphins. They are cold-blooded, lay eggs, and lack advanced cognitive abilities and social behavior.

In conclusion, among the options provided, the dolphin is the closest to