method
//specifically the "get" portion which by default is on.
p. 151 "If the method attribute is not used, the form data will be sent using the get method."
So to not be able to bookmark someone would have had to manually set method to method="post" vs method="get" (default).
//This question is almost a trick in that it isn't mentioned specifically in the book nor is it in the video for "forms" in the course. It is only mentioned once at WGU when you do the google form test at the end of the form chapter, which I've included below:
Question: How does method="get" process form data?
Answer: Appends the form data to the URL so that it is visible. This is great for non-secure data, like a Google search, because the user can bookmark the results that include the values entered in the form.
A better definition can be found here: http://www.w3schools.com/tags/att_form_method.asp