This is a hard question as you cannot talk about where they are from as they are both British but:
I believe that in Interpretation A, the writer had just looked at the body movements and believed they enjoyed it as he says 'it seemed to me', indicating that there is bias in what he is saying. However, in Interpretation B, there is little bias as he had caught proof of the Hitler Youth Camp used as a preparation for the army and unlike the writer in Interpretation A, he asked one of the boys what they did last night, he said pistol-shooting. But with the presence of one leader and many other people, he was obliged to say it was 'good fun' and not a 'military passtime'.
