The correct answer is Secretary of state.
President is the only person who appoints secretary of state to deal with foreign policies.
The secretary of state undergoes a confirmation by hearing before the committee of the senate which deals with foreign relations and then is being confirmed by the senate of the country.
Secretary of the state has some responsibilities, for example, advises the president on issues which are related to foreign policy, he or she can terminate an agreement or treaty or can have a negotiation which is related to foreign affairs of a country. He supervises countries' foreign services.
