Which of the following is the most credible source?
A. The results of an internal investigation by a major corporation,
posted on the company's website
B. An opinion article on the Democratic Party's website written this
year that criticizes the policies of Republicans
C. An opinionated book by climatologists lan Wright and Ryo Saito
published last year about climate change
D. Original charts and graphs displayed on the blog of Peter
Wilkerson, a popular activist and Internet personality

An information source can be defined as a system or medium through which informations, knowledge and ideas may be gotten and used by an individual. All information source to be used in a literary work are expected to be unbiased, trustworthy, reliable and credible.

A credible source is an information or service source that is unbiased, trustworthy and reliable. Also, a credible source typically has pedigree and a track record of excellence service to consumers or end users.

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

In this scenario, original charts and graphs displayed on the blog of Peter Wilkerson, a popular activist and Internet personality is the most credible source. Since the blog contain charts and graphs that are original, it simply means that they're backed by evidence and can be found or obtained from multiple information sources.