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In relation to the acoustic characteristics, consider the following sentences:
1. When producing monophthongs, there is no obstruction to the escape of air through the mouth, and they are all voiced, i.e. the vocal cords vibrate in the air flow.
2. When producing diphthongs, there is no obstruction to the escape of air through the mouth, and they are all voiced.
3. When producing consonants, restrictions to the air flow can be made in various ways, each giving a different characteristic sound.
Choose the correct alternative.