Words are arbitrary symbols and are（） identities so far as their

Words are arbitrary symbols and are（） identities so far as their outer facet — spelling and pronunciation, is concerned.
A、independent
B、reliable
C、stable
D、unsteady
【正确答案】：A
【题目解析】：词就其外部方面拼写和发音而言是具有任意性的符号和独立的单位。