The correct answer is option 4: 1, 2, and 3.

The flying squirrel, porcupine, and barking deer are all naturally found in India.

The flying squirrel, as the name suggests, has the ability to glide through the air. These small mammals have loose folds of skin between their limbs that allow them to move from tree to tree effortlessly. They can be found in various parts of India, especially in forested areas.

Porcupines are known for their sharp quills which they use for self-defense. They are typically found in forested regions and grasslands. India is home to several species of porcupines, making it a natural habitat for these animals.

Barking deer, also known as muntjacs, are small deer species found in the Indian subcontinent. They are known for their distinctive bark-like vocalization, which is used to communicate with other deer. Barking deer are primarily found in forests and grasslands throughout India.

Therefore, all three animals - flying squirrel, porcupine, and barking deer - are naturally found in India.