When attaching a digital document to an email message,which of these is often the best file format to use if recipients are worried about viruses?

A) PDF
B) XML
C) MS Word
D) PDQ
E) DVD

PDF files are typically viewed using Adobe Acrobat Reader and do not contain executable code. This makes them less susceptible to carrying viruses in comparison to file formats like MS Word which can contain macros that may be malicious. Therefore, PDF is often the better choice when sending digital documents via email.