which one of these is a proper use by the president of their foreign policy power to recongnize a foreign nation

putting a u.s embassy in a foreign country
negotiation a tresty with a foreign country
appoiting a foregn country's secretary of state
sending diplomats to a foreign country

The proper use of foreign policy power by the president to recognize a foreign nation would be sending diplomats to a foreign country. This is a diplomatic and official way of establishing formal diplomatic relations with a foreign country.