Step 1: Understanding the question.
The question asks for the correct sequence of authors associated with the documentation or study of the A·chik (Garo) language and literature. Each name mentioned is significant in the linguistic and literary history of the Garo language.
Step 2: Analysis of authors.
- B. W. J. Williamson was among the early contributors to the study and analysis of A·chik language structure.
- A. William Robinson followed in similar research documenting A·chik linguistic patterns.
- C. John Elliot made further comparative linguistic observations.
- D. Nathan Brown contributed to translation and early linguistic development.
Step 3: Logical sequence.
The correct chronological and scholarly sequence is B, A, C, D, representing the development of A·chik linguistic research over time.
Step 4: Conclusion.
Hence, the correct answer is (3) B, A, C, D.