Which of these instruments was invented in the United States?

The banjo is a stringed instrument with a thin membrane stretched over a frame or cavity to form a resonator. The membrane is typically circular, and usually made of plastic, or occasionally animal skin. Early forms of the instrument were fashioned by African Americans in the United States. The banjo is frequently associated with folk, bluegrass, and country music, and has also been used in some rock, pop, and hip-hop. Along with the fiddle, the banjo is a mainstay of American styles of music, such as bluegrass and old-time music. It is also very frequently used in Dixieland jazz, as well as in Caribbean genres like biguine, calypso, and mento.

Source: Wikipedia