Read the following article and select the best answer. Article: The following are the results of the tests done by "Family and Home Magazine" on some Pocket Tape-Recorders on the market now. Pearlcorder S702 $64 This simple model at the bottom of the Olympus range scored the most points for its excellent quality of recording. Background noise hardly affects the sound and recording from a pocket is perfectly possible, but it doesn't turn off automatically. Tape length: 30minutes per side. Weight: 240g. Sony M9 $49.95 Small and very good looking, Sony's latest offering scored most for its appearance. Sounds clear, but there is slight machine noise. The big control buttons are a great improvement on some of the complicated little controls on other tape-recorders. It doesn't switch off automatically, but a red light shows if the machine is still running. Tape length: 60minutes per side. Weight: 195g. Sony M400 $115 Lots of little control buttons that make a noise are difficult to use. Recording is good but machine noise loses points. Tape counter and automatic switch-off when tape has finished recording or rewinding are useful. Tape length: 60 minutes per side. Weight: 230g. Imperial OEM MC7 $ 29.95 Cheap and simple compared with the rest, but recording is good as long as there is no background noise. Use only its own-make of cassette. No light to show it is on; no fast-forward button and the record button makes a loud noise. Tape length: 30 minutes per side. Weight: 285g. Philips 585 $80 Handsome and simple to use, but recording is very poor at more than the recommended distance of 5 cm-designed for dictation. No recording light. Tape length: 15 minutes per side. Weight: 220g. Question: What disadvantage does only the Imperial OEM MC7 have? - No light shows when it is on. - It requires a special cassette. - It picks up background noise. - The record button makes a noise.
A:
It requires a special cassette.