Which of the entries below does not follow best practice for indexing titles of publications?

Which of the following sentences contains an error in number usage, style, or consistency?

Which of the following sentences uses correct punctuation?

Review the following examples of main headings for index entries. Which example does not follow best practice for creating main headings?

Which of the underlined parts of the following sentences contains an error or inconsistency?

Which of following sentences contains an error in punctuation?

Which of the following is the proofreader's mark to indicate where a comma should be inserted?

Does the following sentence have correct spelling? There were alot of odd occurrences on Halloween.

Fill in the blank: On the ___ day of Christmas, My true love gave to me, 12 drummers drumming...

The Chicago Style is very specific in regards to proofreader's marks. Which of the following is the proofreader's mark to indicate when something should be moved to the right?

Which of the following is the proofreader's mark to indicate when a proofreader should insert here, or make subscript?