Answer: Secretary of State
Step-by-step explanation:
Secretary of (insert field of expertise) is the advisor to the President on their respective field (a cabinet is the President's group of advisors).
Speaker of the House (if the President is hurt takes over vice president) and President Pro Tempore (if just the Vice President is hurt, takes over as Vice President) are members in the line of succession.
While Chief Justice is a position the President nominates for that is not part of the Executive Branch (the President's branch).