Which source would be most appropriate for researching the question "How does social media affect personal relationships?"

The most appropriate sources that can be used is a journal article by a psychologist who is studying social media a social media site showing the process of connecting to other users.

In conducting research, the researchers must cite credible and valid sources. A blog post and a Wikipedia page are commonly unsuitable sources to utilize if there are other more credible and valid sources accessible, which for this situation is the journal article.  

when making an inference, the reader should be sure to support the inference with

evidence

a is an educated guess about what will happen.

c. prediction

when new information proves that a reader's prediction is wrong, the reader should

make a new prediction based on the new information.