Final answer:
A US Senator is elected by a popular election as established by the 17th Amendment to the US Constitution. Unlike the President, who is elected via the Electoral College, or Supreme Court justices, who are nominated by the President and confirmed by the Senate, Senators are directly elected by the people of the states they represent.
Step-by-step explanation:
A person becomes a US Senator as a result of a popular election. This means that the senators are elected by the citizens of the states they represent, rather than being chosen through methods such as the Electoral College, appointment by the president, or decisions by the Supreme Court. The 17th Amendment to the United States Constitution established the direct election of US Senators by the people.
It's important also to understand that while the US President is elected through an indirect method known as the Electoral College, the justices of the Supreme Court are nominated by the President and confirmed by the Senate, according to Article II, Section 2 of the Constitution. Judges and Supreme Court justices are not elected by a popular vote. Therefore, the correct answer to the student's original question is option (b), popular election.