Step 1: Amendment Chronology.
- First Schedule: Amended per Indo-Pakistan agreements, transferring territories (B).
- Schedule IX: Added via First Amendment in 1951 (A).
- Preamble: Amended in 1976 to include "Socialist" and "Secular" (D).
- Mizoram: Became a state in 1987 (C).
Step 2: Ordered Sequence.
The chronological sequence is as follows:
(A) B: First Schedule amendment (territory transfer).
(B) A: Schedule IX addition.
(C) D: Preamble amendment.
(D) C: Mizoram statehood.
Step 3: Summary.
Therefore, the correct order is (B) A, B, D, C.