Which part of Article II, Section 2 of the US Constitution gives presidents the power to fulfill one of their roles as chief diplomat?

“He shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors.”
“He shall nominate, and by and with the Advice and Consent of the Senate, shall appoint . . . Judges of the supreme Court.”
“He shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur.”
“The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States.”