Step 1: Identify the establishment year of each documentation center:\[\begin{array}{rl} \bullet & \text{(D) INSDOC (Indian National Scientific Documentation Centre): Established in 1952.} \\ \bullet & \text{(A) DESIDOC (Defence Scientific Information & Documentation Centre): Started as the Scientific Information Bureau in 1958.} \\ \bullet & \text{(B) DRTC (Documentation Research and Training Centre): Established by S.R. Ranganathan in 1962.} \\ \bullet & \text{(C) NASSDOC (National Social Science Documentation Centre): Established in 1969.} \\ \end{array}\]
Step 2: Arrange the establishment years chronologically: 1952, 1958, 1962, 1969.
Step 3: Assign each center to its corresponding year. The resulting sequence is INSDOC (D), DESIDOC (A), DRTC (B), and NASSDOC (C), giving the order (D), (A), (B), (C).