单选题 Two sounds are in free variation when they occur in the same environment and do not contrast, namely, the substitution of one for the other does not produce a different word, but merely a different pronunciation.
【正确答案】 A
【答案解析】解析：自由变体是指两个音素出现在一个相同的语音环境中，并不区别意义，即用一个音素替换另一个音素不产生新词，只产生同一个词的不同读音。