A credible source refers to a source that is reliable, is not subjective and is backed with evidence like research articles from authors that are recognized and academic databases. According to this, the answer is that the resource that would be considered most credible is an article published in a scientific journal. The other options are not credible sources because an article on Wikipedia, a blog about the writer's own experiment and an essay about science in a popular magazine are sources that may contain the author's opinion who usually is not identified or an expert in the subject and these sources are not trustworthy.
An essay is more opinionated than a report. while you can give facts and reasons in both, this topic already has a bias towards why it's not important. A report would just state the facts on the importance of cooking, good or bad. While an essay would try to convince you that it's not important and give facts and reasons towards that bias.
A staff meeting to introduce new employees would be an appropriate setting to use jargon. Jargon is language familiar to a certain profession and so in this case it will allow the new employee to recognize the jargon.
