Bias is a skewed opinion that is caused by outside influences; it causes information not to be presented in a completely accurate manner.
Based on the given information, the article with the most bias would most likely be C. It was written by a company which produces computers, and the article is refuting the idea that computers are damaging to eyesight. A computer company would not want screentime to have an adverse effect on eyesight because it would hurt their business so this article is the least reliable because it may present some of the information inaccurately in order to help their cause.
Hope this helps!!
