Hello!
The correct answer to your question is C: candidates' websites.
Websites for candidates often tend to be biased. The intention of the website is to convince and persuade voters to vote for the candidate. In order to do this, the website may contain biased information that is of use to the candidate. The biased information on the website is intended to persuade people into agreeing with the beliefs of the candidate.
I hope this helps you! Feel free to comment or PM me with any additional questions that you may have on the topic!