The morpheme of the past tense m

The morpheme of the past tense marker /-ed/is pronounced as/t/in worked,/d/in lived, and /I d in landed.This example shows ______.
A、morphemes are abstract units
B、morphs are actual spoken,minimal carriers of meaning
C、allomorphs are phonetically conditioned and thus predictable
D、monomorphemic words coincide with words and function freely in a sentence
【正确答案】：C
【题目解析】：过去时标记词/-ed/的语素在worked，在lived，读作/t/，在landing，读作/I d。这个例子表明，同义异构体是受语音制约的，因此是可以预测的。