Correct Option (d):
If the annual Union Budget, which is a Money Bill, fails to be passed by the Lok Sabha, it signifies that the government of the day has lost the confidence of the House. Under the principle of collective responsibility enshrined in Article 75(3) of the Indian Constitution, the Council of Ministers is collectively responsible to the Lok Sabha. The rejection of a Money Bill, particularly the Budget, is considered a vote of no-confidence against the government. Consequently, the Prime Minister and the entire Council of Ministers are constitutionally obliged to resign.
Incorrect Options:
Option (a): The Budget is not simply modified and presented again. The rejection of the Budget by the Lok Sabha indicates a fundamental loss of parliamentary confidence in the government, which necessitates a more significant constitutional action than mere modification.
Option (b): The Rajya Sabha has limited powers concerning Money Bills, including the Union Budget. It can only make recommendations, which the Lok Sabha may or may not accept. The Rajya Sabha cannot reject or amend a Money Bill, nor can it prevent its passage. Therefore, referring the Budget to the Rajya Sabha for suggestions does not resolve the constitutional crisis arising from its rejection in the Lok Sabha.
Option (c): The principle of collective responsibility dictates that the entire Council of Ministers is accountable to the Lok Sabha. The resignation of only the Union Finance Minister would not address the loss of confidence in the government as a whole, which is implied by the rejection of the Budget. The entire Council of Ministers, led by the Prime Minister, must resign.