Final answer:
Presidents require 270 electoral votes to win to secure a majority within the 538-member Electoral College, which is designed to prevent deadlocks and reflect a majority selection not directly tied to the popular vote.
Step-by-step explanation:
Presidents need at least 270 electoral votes to win the presidency because it ensures a majority in the Electoral College. The Electoral College consists of 538 electors, with each state being allocated a number of electors equal to the number of its Senators and Representatives, and Washington, DC having electors as if it were a state. The requirement of 270 votes is more than half of the 538 total, which helps to prevent deadlocks in Electoral College voting and ensures that the winning candidate has a majority of the electors' support.
The framers of the Constitution designed the Electoral College system to balance the influence of populous and less populous states, though it is not directly related to balancing power with the Senate (option b) or to align with the number of congressional districts (option d). The system does not guarantee that the president receives a majority of the popular vote (option a), as the Electoral College allows for the possibility that a candidate can win the presidency without winning the national popular vote, as has occurred in several elections.