Challenges to and restoration of the congress system

Read the passage and answer the questions below:
…Indira Gandhi changed the Congress into highly cerntalised and
undemocratic party organisation, from the earlier federal, democratic
and ideological formation that Nehru had led…..But this… could not
have happened had not Indira Gandhi changed the entire nature of
politics. This new, populist politics turned political ideology ……. into
a mere electoral discourse, use of various slogans not meant to be
translated into government policies…… During its great electoral
victories in early 1970s, amidst the celebration, the Congress party as a
political organisation died….. — Sudipta Kaviraj
(a) What according to the author is the difference between the
strategies of Nehru and Indira Gandhi?
(b) Why does the author say that the Congress party ‘died’ in the
seventies?
(c) In what way, did the change in the Congress party affect other
political parties also?