Cannot raise either arm to top of head as if to put on a hat

I’m sure there is an answer somewhere, but how would a decision maker know from reading the ESA50 questionnaire that a claimant fits this descriptor?  (Activity 3 , Descriptor B).  On the ESA50 there is a question about being unable to raise either arm to put something in top pocket (Descriptor A 15 points), a question about raising either arm above your head (Descriptor C 6 points) and having no problems (Descriptor D, 0 points).

But in the absence of the HCP specifically asking this in a face to face interview, how would anyone ever be allocated Descriptor B?