Kathasaritsagara, a literary work, was originally composed in which of the following languages?

The correct option is Sanskrit.

Detailed Explanation:
- Kathasaritsagara (literally meaning "Ocean of the Streams of Stories") is a famous 11th-century collection of Indian legends, folklore, and fairy tales.
- It was composed in classical Sanskrit by the Kashmiri poet Somadeva around the 11th century CE for the entertainment of Queen Suryamati, wife of King Ananta of Kashmir.
- Somadeva compiled this monumental collection based on an earlier, now-lost narrative work called Brihatkatha, which was originally composed in the Paisaci language by Gunadhya.