Concept:The modal verb "must" requires an infinitive verb form to express obligation in passive voice.Explanation:The phrase "must received by Friday" is grammatically incorrect.The verb "received" needs the auxiliary verb "be" to form the passive construction.The correct phrase is "must be received by Friday".This passive form correctly conveys that the application will be received by someone.Therefore, the error is in part (c) of the sentence.Answer:(c)