In a group discussion, which of these is the best example of challenging the
credibility of a source?
A. Constance Miller's interpretation of Sense and Sensibility is
interesting but ultimately flawed.
B. Henry Taylor's article keeps saying that Victor Hugo was against
Napoleon, but he never backs it up.
C. I disagree with Alex Fernandez that Tom Joad represents the
"everyman;" he represents the outcast.
D. Car crashes play a big role in Fitzgerald's The Great Gatsby and
This Side of Paradise.

A credible source is an information source that is unbiased, trustworthy and reliable. Also, a credible source is typically backed up by evidence from various information channels and should be accurate.

In order to validate a credible source, it is necessary to ensure that the information provided is checked against other reliable sources to verify its level of accuracy.

As a rule, any credible information source should have multiple ways to validate the informations being presented i.e it should be factually backed up with evidence.

In a group discussion, the best example of challenging the credibility of a source would be; Henry Taylor's article keeps saying that Victor Hugo was against Napoleon, but he never backs it up. Henry's article isn't credible because it isn't backed up with any evidence or source to validate the claim that Victor Hugo was against Napoleon.