A phoneme is defined as（ ）.
a minimal meaningful unit in the grammatical system of a language
a minimal distinctive unit in the grammatical system of a language
a minimal distinctive unit in the sound system of a language
a minimal meaningful unit in the lexical system of a language
本题考查音位的含义。
音位被定义为在语言的发音系统中最小的具有甄别性特征的单位。
