Which of the following are useful in overcoming the communication barriers in…

Classroom communication succeeds when the message the teacher intends matches what the student decodes; a barrier is anything that distorts that match, and a technique overcomes a barrier only if it actively reduces distortion — either by adding redundancy so the core idea survives, by using paralinguistic cues such as tone and pitch to disambiguate meaning, or by anchoring new information in a context the listener already shares.

Checking each option against that standard: identifying the level of redundancy (a) lets a teacher judge how much repetition a message needs so it survives even if a word or two is missed. Voice inflexion (e), variation in pitch and tone, sustains attention and signals emphasis, cutting down ambiguity. Contextualizing the speech (f) ties unfamiliar terms to a setting students already recognise, so meaning is inferred rather than lost. Each of these actively removes distortion, which is why the combination that overcomes the barriers is (a), (e) and (f).

• Use of unfamiliar words (b): adds jargon the listener must decode instead of removing distortion, so it works against communication rather than for it.

• Ignoring the students' vocabulary (c): discards the receiver's existing frame of reference, breaking the shared ground a message needs to land.

• Fragmented sentences (d): disorganised syntax breaks the structure of the message itself, adding distortion rather than clearing it.

So the set of items that actively overcome classroom communication barriers is (a), (e) and (f), matching ‘Only (a), (e) and (f)’.