The odd one out is D, Sonata. The other three options are all musical instruments, while a sonata is a piece of music written for one or more instruments.
A mouth organ, also known as a harmonica, is a free-reed aerophone that is played by blowing air through one or more holes in the instrument. The reeds vibrate in response to the air, producing sound.
An electric guitar is a stringed instrument that is played by plucking or strumming the strings. The strings are amplified by an electric pickup, which converts the vibrations of the strings into an electrical signal.
A keyboard is a musical instrument that is played by pressing keys. The keys are connected to levers that strike metal bars, which produce sound.
A sonata is a piece of music written for one or more instruments. It is typically in three movements, and the first movement is usually in sonata form. Sonata form is a musical structure that consists of an exposition, development, and recapitulation. The exposition introduces the main themes of the piece, the development explores these themes in more detail, and the recapitulation brings back the main themes in a new way.