The correct answer is option 4 - Vishnu Sharma. Vishnu Sharma is the author of the book Panchatantra. The Panchatantra is an ancient Indian collection of interrelated animal fables. It is believed to have been written in Sanskrit in the 3rd century BCE by Vishnu Sharma, a scholar and teacher to the sons of the king. The book consists of five books or "tantras" which contain stories that impart moral and practical wisdom. The stories in the Panchatantra often feature animals as the main characters and are known for their cleverness and moral lessons. The Panchatantra has been translated into various languages and has had a significant influence on storytelling and literature across the world. Therefore, the correct author of the book Panchatantra is Vishnu Sharma.