What does a circle around the letters "SP" mean?

Which of the following is the proofreader's mark to indicate where an apostrophe or single quotation mark should be inserted?

Which of the following is the proofreader's mark to indicate where one should insert quotation marks?

A book has five authors. Should you write out all of their names in the bibliography citation?

Which of the following is the proofreader's mark to insert em dash?

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 left?

Which of the following represents the correct way to write the publication information for a cited work in a bibliography?

Read the following passage and select the line that contains an error in punctuation.

Read the following passage and select the line that contains an error in number usage, style, or consistency.

Which of the following statements about typeset matter is correct?

Which of the following statements about typeset matter is correct