Here are the answers to your questions:
Question 1
A) Which words describe a credible source?
Answer: accurate and believable
Question 2
A) Which source would be the most credible for research on the dangers of playing football?
Answer: an article published by a national health organization
Question 3
A) Which description explains when a source is objective?
Answer: It is factual and does not seek to persuade a reader to agree with a certain point of view.
Question 4
A) Which description defines an expert in a particular field?
Answer: The person has a high degree of knowledge about a topic.