In the sentence "Using a moderately powerful desktop computer running a music composition ogramand a ' 500 synthesizer" ( paragraph 2 ), the word "moderately" bas the meaning of ______.

A．makes it possible for anyone to write music.
B．is only available in expensive recording studios.
C．requires high -end computers and programming skills.
D．provides cheap, powerful ways of making musi

A．门
B．中庭
C．干墙
D．通道