Step 1: Understanding the Concept:
The question asks to identify the author of the ancient Sanskrit play Svapnavasavadatta (The Vision of Vasavadatta).
Step 2: Detailed Explanation:
Svapnavasavadatta is one of the most celebrated plays in Sanskrit literature. It is attributed to the ancient Indian playwright Bhasa, who is considered one of the earliest and most significant figures in Sanskrit drama, predating even Kalidasa. The other authors are known for different works: Kalidasa for plays like Abhijnanasakuntalam, Bhavabhuti for Uttararamacarita, and Mohan Rakesh for modern Hindi plays like Adhe Adhoore.
Step 3: Final Answer:
The writer of Svapnavasavadatta is Bhasa.