Step 1: Understanding the context of the question.
This question focuses on the term Khurumai kokthai, which is closely related to the Kokborok language. The answer requires identifying the correct term for Kokborokni.
Step 2: Analyzing the Options.
- (1) Dimasani kokthai: Not the correct term related to Kokborokni.
- (2) Boroni kokthai: Incorrect, as this term does not match the required cultural or linguistic classification.
- (3) Kokborokni kokthai: This is the correct term that matches the context of Kokborok.
- (4) Garoni kokthai: Does not match the specific linguistic or cultural classification.
Step 3: Conclusion.
Thus, the correct answer is Kokborokni kokthai, as it matches the linguistic context.