D - loyalty ... motif
The loyalty of Argos is not a theme throughout the story of the Odyssey, neither is it a theme of hospitality. The only other answer that comes into play is motif due to that fact that similes and epithets are not really used in this context, for that reason motif is the only other available one.
And because the answer is either A or D, and it's not A, we can conclude it's D.