A majority of 100 U.S. senators would be more than half. To find the majority, you take half of 100, which is 50, and then add 1. Therefore, a majority would be 51 senators. Since 51 is not one of the provided options, the closest correct answer to indicate a majority is 50, understanding that 50 alone is not a majority but indicates the threshold.
However, to clarify, a true majority requires 51 senators.