The answer is derived from the passage describing Indira Gandhi's centralised style versus Nehru's federal style. Option (a) reflects Indira Gandhi's approach, described in the text as 'centralised and undemocratic', leading to the party 'dying' as an organisation. Options (b), (c), and (d) reflect the earlier era or democratic alternatives. The text notes that the earlier 'federal, democratic' formation (associated with senior leaders like the 'Syndicate') had the advantage of being ideological but suffered from 'internal factionalism' and 'internal differences', which the opposition used to challenge the Congress.