The correct answer is (A): (A), (B), (C) Only
(A) The election of 1989 marked the end of the Congress system as it led to the formation of a non-Congress government at the center, reflecting a shift in Indian politics.
(B) The assassination of Rajiv Gandhi by LTTE occurred in 1991 and had significant political ramifications.
(C) In 1989, the UPA reforms were initiated by V.P. Singh, who was the Prime Minister at that time.
(D) In 1989, the UPA did not form the government; it was a coalition government led by the National Front, with V.P. Singh as the Prime Minister.
(E) Kapoori Thakur, the then Chief Minister of Bihar, was not a pioneer in introducing the policy of reservation during the 1990s.