In 1984, the Congress Party in India won a landslide victory in the general elections following the assassination of Prime Minister Indira Gandhi. The party secured a significant majority in the parliament, winning a large number of seats. The correct answer to the question is option 'B', which states that the Congress Party won four-fifths of the total seats in the election.

Explanation:
The Indian Parliament consists of two houses - the Lok Sabha (Lower House) and the Rajya Sabha (Upper House). The Lok Sabha is directly elected by the people of India, while the Rajya Sabha is elected by the members of state legislative assemblies.

The total number of seats in the Lok Sabha is 543. Therefore, to determine the number of seats won by the Congress Party in 1984, we need to calculate four-fifths of 543.

Calculation:
4/5 x 543 = 434.4

Since the number of seats cannot be in decimal, we round off the result to the nearest whole number. Therefore, the Congress Party won approximately 434 seats in the Lok Sabha in 1984.

Conclusion:
In 1984, the Congress Party won approximately four-fifths of the total seats in the Lok Sabha, which amounted to around 434 seats. This massive victory was largely attributed to the sympathy wave following the assassination of Prime Minister Indira Gandhi. It allowed the Congress Party to form a strong government and retain power at the center.