Final answer:
Option C is an inappropriate use of "you" as it directs personal blame, which can come across as accusatory. It is better to rephrase negative messages to focus on the situation, not the individual.
Step-by-step explanation:
The inappropriate use of the word "you" in a negative message among the given options is C) You shouldn't have washed that wool shirt; it should be dry cleaned only. This use of "you" is inappropriate because it delivers a direct and personal criticism, which can sound accusatory and confrontational. To convey a negative message more effectively, it is better to focus on the situation rather than the person. For instance, it could be rephrased as "That wool shirt requires dry cleaning to maintain its quality." This approach avoids direct blame and centers the attention on the action and item in question.