When the annual Union Budget is not passed by the Lok Sabha,

1. The passage of the annual Union Budget, which includes the Appropriation Bill and the Finance Bill, is considered a matter of confidence in the government. 2. The Lok Sabha holds the power of the purse and exercises control over the executive, primarily through financial control. 3. If the Union Budget is not passed by the Lok Sabha, it signifies that the government (the Council of Ministers) has lost the confidence of the House. 4. According to the principle of collective responsibility enshrined in Article 75(3) of the Constitution, the Council of Ministers is collectively responsible to the Lok Sabha. 5. Failure to pass the Budget is treated as a vote of no-confidence, leading to the constitutional obligation for the government to resign. 6. Consequently, the Prime Minister, as the head of the Council of Ministers, submits the resignation of the entire Council of Ministers. 7. Referring it to the Rajya Sabha (Option B) is not the procedure, as Rajya Sabha has limited powers regarding money bills. Asking only the Union Finance Minister to resign (Option C) ignores the principle of collective responsibility. Modifying and presenting again (Option A) does not resolve the underlying loss of confidence.