Branch managers of First Federated Savings and Loan received this e-mail message: Please inform all personal that management retains the right to check personal belongings of employees before employees leave the bank. What error did the writer make?
a. A grammatical mistake
b. A proofreading error
c. A failure to use spell check
d. No error was made. The sentence is correct as written

b) A proofreading error

Explanation:

Proofreading error is the issue that occurs when final level of editing on any content is not done through checking spellings, punctuation mistakes,grammatical mistakes etc.

According to the question,statement in email message received by branch manager persist proofreading mistakes which includes spelling errors, punctuation mistakes and other surface errors.

Other options are incorrect because grammatical error, unsuccessful in using spelling check or error-less sentence is not depicted through emails message statement.Thus, the correct option is option(b).