You ask for feedback on a proposal and are told "I don't believe your claims. Your facts must be wrong." You are confident that your facts are indeed correct. You should:

a. write a memo to the proofreader's supervisor before sending the final proposal
b. make your claims more moderate because you must adapt your message to the audience.
c. document the source f your facts and give more information back up your claims.
d. delay sending the proposal until the reader's reaction changes.

Is C the most suitable answer?

I agree with C. B is also worth thinking about, but it depends on the writer's level of confidence.

thank you

Yes, C is the most suitable answer in this situation. When faced with a skeptical response to your proposal, it is important to provide supporting evidence and additional information to back up your claims. By documenting the sources of your facts and offering more context, you can address the reader's concerns and demonstrate the accuracy of your information. This approach allows you to effectively communicate your message and build credibility with the reader.