An idiom consists of at least two words. Each has a single mean

An idiom consists of at least two words. Each has a single meaning and often functions as one word. This is called （ ）.
A、semantic unity
B、structural stability
C、rhetorical function
D、none of the above
【正确答案】：A
【题目解析】：一个习语至少由两个词组成。每一个词都有一个单一的含义，通常作为一个词发挥作用。这叫做语义的整体性。