The correct answer is D. Mario should not use the source. It has not been peer-reviewed.
Step-by-step explanation:
Before including any source in a research paper of any topic it is necessary to evaluate whether the source is reliable and credible, this depends on whether the author is known and an expert in the field; whether the information is updated and whether the information has been peer-reviewed, which means it has been checked and approved by other experts.
In the case of Mario, the source he found has a known author and seems to be updated as it was written recently; however, this has not been peer-reviewed and this implies the information has not been approved by other experts. This makes the source less reliable and credible and thus Mario should not use the source because it has not been peer-reviewed.