The correct answer is B. President.
Step-by-step explanation
The executive power is one of the three branches of the public power of a state. and its functions are to execute laws, represent the country diplomatically, sign treaties, appoint ambassadors, appoint members of the Supreme Court, and propose laws to Congress to improve its work. In representative democracies, the president is the public office referred to as the main member of the executive power of a State. According to the above, the correct answer is B. As head of the executive branch, the president can sign treaties, appoint ambassadors, appoint justices to vacancies on the Supreme Court, and propose laws to Congress.