Step 1: Understanding the question.
Gatha Saptasathi is an ancient text written in Prakrit that is attributed to the king Hala. It is a collection of 700 verses dedicated to Lord Shiva and his devotees.
Step 2: Explanation of the options.
- (A) Rudra Varma: Rudra Varma was not the writer of Gatha Saptasathi.
- (B) Simuka: Simuka is not associated with the writing of Gatha Saptasathi.
- (C) Hala: Correct. Hala, a king of the Satavahana dynasty, is traditionally credited with composing Gatha Saptasathi.
- (D) Balasri: Balasri is not the writer of Gatha Saptasathi.
Step 3: Conclusion.
Therefore, the correct answer is Hala, who is the author of Gatha Saptasathi.
Final Answer: Hala.