Under what conditions can Congress override a presidential veto?

Congress can override a presidential veto under the condition of a two-thirds majority vote in both the House of Representatives and the Senate. This rigorous requirement ensures that there is significant legislative support for overriding the President's decision, reflecting a strong consensus among lawmakers. The framers of the Constitution designed this process to balance the power between the legislative and executive branches, thereby preventing Congress from easily overturning a veto without substantial agreement.

The necessity of a two-thirds majority underscores the importance of collaboration and compromise within Congress, as it compels lawmakers to gain broader support for the legislation in question. This process is fundamental to the checks and balances principle that governs the U.S. political system. The other options do not align with the constitutional procedures for overriding a veto, which is why they are not considered correct in this context.