Option 1: Fish

Fish breathe through gills, not their skin. Gills are specialized organs that extract oxygen from water.

Option 2: Pigeon

Pigeons, like most birds, have lungs for breathing. They do not breathe through their skin.

Option 3: Frog

The correct answer is option 3. Frogs have a unique respiratory system that allows them to breathe through their skin. Their skin is thin and moist, enabling oxygen to diffuse directly into their bloodstream. This process is known as cutaneous respiration and is especially important for frogs that live in aquatic or semi-aquatic environments. In addition to breathing through their skin, frogs also have lungs and can use both methods to obtain oxygen.

Option 4: Cockroach

Cockroaches have a different respiratory system compared to frogs. They have tiny openings on their body called spiracles, through which air enters their tiny air tubes called tracheae. Oxygen is then carried to the cells through this network of tracheae. Cockroaches do not rely on their skin for breathing.

In conclusion, the correct answer is option 3, as frogs are the animals that can breathe through their skin.