A) The semantic level
B) The syntactic level
C) The Freudian level
D) The phonological level

A) Different vowels are produced by varying manners of articulation ways of constricting the air stream in the oral cavity and places of articulation locations where the air stream is constricted. Motor delays
B) Different vowels are produced by varying places of articulation ways of constricting the air stream in the oral cavity and manners of articulation locations where the air stream is constricted.
C) Different consonants are produced by varying manners of articulation ways of constricting the air stream in the oral cavity and places of articulation locations where the air stream is constricted
D) Different consonants are produced by varying places of articulation ways of constricting the air stream in the oral cavity and manners of articulation locations where the air stream is constricted.

A) Do not show what acoustic properties define phonemes
B) Show clearly what acoustic properties define phonemes
C) Only show what acoustic properties define phonemes when speakers articulate clearly
D) Only show what acoustic properties define phonemes when speakers speak Mandarin Chinese