How does voice affect the credibility of a text?

A The voice affects consistency of tone and the amount of bias revealed.
B A positive voice is more credible than a negative voice.
c A negative voice is more credible than a positive voice.
D The voice must express a similar personality to all potential readers.

Question

How does voice affect the credibility of a text?

A The voice affects consistency of tone and the amount of bias revealed.
B A positive voice is more credible than a negative voice.
c A negative voice is more credible than a positive voice. 
D The voice must express a similar personality to all potential readers.

Vocaloid · Answer

old question but will answer so this can be closed

voice is the combination of the author's style/personality that characterizes the piece

using process of elimination
B and C are out (a piece of writing can be positive or negative but that factor doesn't determine its credibility)

D is kind of nonsensical (everybody is going to interpret the voice differently)