How do you identify a complete sentence?

Plzz helpp me out!!

Read this excerpt from “the love song of j. alfred prufrock” and answer the question.let us go, through certain half-deserted streets,  the muttering retreats  of restless nights in one-night cheap hotels  and sawdust restaurants with oyster-shells:   streets that follow like a tedious argument  of insidious intentwhat does the use of the word  muttering  suggest? a feeling of discontentthe noise of city streetsthe inability to be understooda sense of lonelinessit's not c so hel0