Answer:
A. Speakers
Step-by-step explanation:
To hear music stored on a sequencer, you need to connect the sequencer to a device that can convert the digital audio signal into sound waves that can be heard by the human ear. This can be done by connecting the sequencer to a set of speakers, which can amplify and project the sound. An amplifier may also be needed to boost the audio signal before it is sent to the speakers, but the speakers are the essential component for hearing the music stored on the sequencer. A synthesizer is not necessary for playing back music stored on a sequencer, as the sequencer can store and playback pre-recorded audio data. However, a synthesizer can be used to create new sounds and music, which can then be recorded and stored on a sequencer.