According to the pollster, if PR didn't do it, then it must be either a stranger or someone PR knew.
There's several different varieties of 'someone PR knew' types, ranging from JR, BR, their close friends, relatives, and neighbors, to a coworker or employee, a store clerk, a hired hand, a one-time acquaintance, or even someone who PR just heard about.
Not only is there a rather dubious, vague line between 'someone PR knew' and 'stranger', there is yet another possibility: someone JR knew, but was a stranger to PR. This choice wasn't included in the seemingly 'all-inclusive' poll.