Answer:
e. There was not a common repertory of mosaic designs with which artisans who lived in various parts of the Roman empire were familiar
Explanation:
Reverse this assumption: let's say there was a common repertory of mosaic designs.
in this case, that repertory - since it was a common repertory - would have included animal figures from all over the place. (at the very least, it would be quite unreasonable to expect a common repertory to have been restricted to animal figures from the sepphoris area in particular.)
this destroys the argument, because, were there such a repertory, then artists local to sepphoris would have followed it as well, creating the exotic designs despite their status as natives in the area. So, e part is correct.