Final answer:
TRUE. The President pro tempore is third in the line of presidential succession.
Step-by-step explanation:
The President pro tempore is third in the line of presidential succession.
According to the United States Constitution, the line of succession to the presidency starts with the President, followed by the Vice President. If both the President and Vice President are unable to serve, the Speaker of the House of Representatives would take over. After the Speaker, the President pro tempore of the Senate is next in line to assume the presidency.