Which factor is necessary for appearing for presentation
2. Eye contact
3. Tone of presentation
4. Style of delivery
All above given options are surely necessary to be given due consideration prior to appear in presentation. In such cases, when all given options seem close then v need to select best suitable option. What i believe that best option is mannerism coz it covers all factors such as eye contact, tone of presentation as well as style of delivery.
All buddies r discussing grammatical portion a lot as most confusion questions are 'entered' & 'believe'. simply exclude ur 2 score against these qtnz as no body is sure what is rite n rong....controversial point of view exist....i think rite one are