Answer:
B). A Proofreading error.
Explanation:
As per the question, the error made by the writer in this e-mail message is the 'proofreading error' which implies that he didn't recheck his message for grammatical, word choice, formatting, or spelling errors. The proofreading helps in fixing these errors before finalizing it that aids to enhance the comprehension, accuracy, and compactness of the work. The given message contains various errors like prepositional errors(lack of preposition before 'personnel'), use of wrong spelling of 'personnel', the punctuation errors, etc.. Therefore, option B is the correct answer.
