The 'D' paper will not respond to the context of the assignment. It does not fulfill the purpose of the essay. It failed to effectively evaluate the essay, or doesn't respond to the overall purpose of the assignment.
The 'C' paper will have a clear focus on analyzing the essay and will respond to the context of the essay, though possibly not entirely adequately. The summary will be thorough, objective, accurate, and focuses on ideas rather than events. It hits most of the major points from the essay, but may miss a few. The essay will have a clear thesis that identifies the writer's points and will connect to the context for the essay. The thesis should focus on the writer's overall evaluation of the essay based on their chosen criteria, and should acknowledge the purpose of the essay (To use or not to Use, that is the question). The rest of the essay will be organized around the points from the thesis. Each point will have evidence to support it, but some evidence may lack detail or include over-generalized statements. In addition, connections will be made between the evidence and the point it supports, though these connections may be a bit implicit or not made clear for the reader.
The 'B' paper will fulfill all of the criteria for the 'C' paper, and will also: include a focus that is explicitly connected to the context and is clearly maintained throughout the rest of the essay. The evidence will be specific, and will include effective use of textual evidence. Often the strength of evidence will be the difference between a 'B' paper and a 'C' paper. Connections between evidence and points will be clearly made for the reader, and there will be few if any examples that don't have these connections. The essay flows well, incorporating some transitions to effectively lead the reader from one paragraph to the next. In addition, the summary will be concise, but explain thoroughly for the reader the main points of the essay. The essay may have several concerns grammar/mechanics and/or proofreading, but these problems don't seriously interrupt communication.
The 'A' paper will fulfill all of the criteria for the 'B' paper and will also: Make the purpose of the essay especially clear and maintain that purpose exceptionally well throughout the essay. Have exceptionally effective evidence - evidence that is clearly relevant to the point being made, specific, and thoroughly explained - for all point and connects those points back to the thesis. The reader is left with no questions as to the writer's response to the context of the essay. The paper is easy to follow due to effective transitions between all paragraphs. The summary does an excellent job of representing all of the points from the original essay in a concise, accurate and thorough manner. The essay will be free from any mechanical or grammatical concerns.