Final answer:
The Mellotron is the instrument that uses pre-recorded reels of tape to produce musical sounds, notable for its use in classic rock music.
Step-by-step explanation:
The Mellotron is an electro-mechanical musical instrument developed in Birmingham, England, in 1963.
It is played by pressing its keys, each of which causes a length of magnetic tape to contact a capstan, which pulls it across a playback head.
The Mellotron creates music by triggering playback of pre-recorded tape loops when keys on its keyboard are pressed.
This instrument, popular during the 1960s and 1970s, provided musicians with a way to mimic orchestral instruments as well as other sounds without having to have the actual instruments or performers present.
For example, the Beatles used the Mellotron in the intro of their song "Strawberry Fields Forever" to create a flute-like sound.