Arrange the following in chronological sequence: A. Start of external services…

Concept — A chronological-sequence item is settled event by event, never by reading the offered orderings first: each listed event is dated independently against its own year, and those years are then sorted in ascending order. The ordering that reproduces the sorted years is the accepted sequence.

For India's mass-media milestones four anchor periods carry almost every such item — the arrival of sound cinema in the early 1930s, the reorganisation of state broadcasting in the mid-1930s, the wartime opening of overseas broadcasts at the end of the 1930s, and the building of government media institutions immediately after Independence.

Application

Dating each listed event on its own evidence:

1. ‘Alam Ara’, made by Ardeshir Irani for the Imperial Film Company, premiered in Bombay on 14 March 1931 and is India's first sound feature — the year is 1931.

2. The Indian State Broadcasting Service, already run as a separate government department under the Controller of Broadcasting since 1935, was renamed All India Radio on 8 June 1936 — the year is 1936.

3. The External Services of All India Radio opened on 1 October 1939 with a broadcast in Pashto directed at listeners beyond the north-western frontier, a wartime measure — the year is 1939.

4. The Films Division was set up by the Government of India in 1948 to produce documentaries and newsreels for the newly independent state — the year is 1948.

Cross-check

• The sequence C, B, D, A puts the Films Division of 1948 immediately after the 1931 film, ahead of both the 1936 renaming and the 1939 external services.

• The sequence A, B, C, D merely repeats the order in which the four events are listed in the question; it opens at 1939 and reaches 1931 only in third place.

• The sequence D, C, A, B places the 1936 renaming of the broadcasting service before the 1931 release of the talkie, inverting that single pair.

• A useful memory anchor: cinema found its voice before broadcasting found its name, and both happened before the Republic built its own film institution.

Sorting the four years ascending — 1931, then 1936, then 1939, then 1948 — gives the sequence C, D, A, B, which is the accepted answer.