Which questions would determine whether an article is scientifically accurate? is the author stating an opinion or a fact? does the author have a balanced diet? does the author have evidence for the given facts? how many articles has the author written before? does the author like music?

Option A and C

Explanation:

When the question A is asked "whether the author's statement is an opinion or fact?" then the answer to this question will definitely help to determine whether the author has written a scientific article or not. If the author states that he has expressed his opinion then such articles cannot not be considered as scientific article.

Likewise if the author has given appropriate and sufficient evidences to prove the fact that he had mentioned in his article then  such articles will definitely fall into the category of scientific article. Hence option C is correct.

Question B, E are totally irrelevant

While question D is just a way to analyse whether the author is renowned author  who publishes sensible article or he is a new comer. This question is basically to check the authenticity of the author writing skills.