Which TV theme begins with the words: “You know we belong together…”?

Who is the main character in the TV show "Sherlock," a modern adaptation of Sir Arthur Conan Doyle's Sherlock Holmes detective stories?

Richie Cunningham, Ralph Malph, Chachi Arcola, and Joanie Cunningham

Richie Cunningham, Fonzie, Joanie Cunningham, and Marion Cunningham

 Richie Cunningham, Fonzie, Potsie Weber, and Ralph Malph

 Richie Cunningham, Howard Cunningham, Ralph Malph, and Joanie Cunningham