The order of information is logical, and the reader can follow it because of well-chosen transitions. Paragraph divisions are logical, and the paragraphs use enough specific detail to make their point tellingly. The expression is competent, more ambitious than that of the C paper, less felicitous than that of the A paper. Not only is sentence structure correct, but it also uses subordination, emphasis, sentence length and variety, and modifiers effectively. It would be surprising to find serious sentence errors comma splices, fragments, or fused sentences in a B paper.
Word choice is idiomatic, vocabulary precise.
Punctuation, grammar, and spelling conform to the conventions of edited American English. The assignment has been followed. The paper develops its points with a sense of audience. The information and degree of persuasion in a C paper is appropriate. There is evidence and though the evidence is perhaps obvious and easily accessible, it has been gathered honestly and used responsibly.