Which is not one of justinian’s achievements?

a.
he created a code of law that unite the byzantine empire and later served as a model for the codes of law in many modern nations.

b.
he doubled the size of the empire and ruled much of the mediterranean world.

c.
he built a huge domed cathedral called the hagia sophia, an enormous underground aqueduct, and a fabulous palace complex.

d.
he moved the imperial capital from rome to byzantium, so it would attract people from all over the world.

This was the item NOT one of Justinian's accomplishments:

It had been Constantine, a couple centuries prior to Justinian, who had moved the imperial capital from Rome to Byzantium, renaming it Constantinople.   Constantine remade the city as his capital city in monumental fashion, and wanted to give it also the prestige and aura of the Roman Empire. The building of Constantinople took several years, and Constantine modeled it after Rome, with government buildings designed in Roman style.  

The existing city of Byzantium was the place Constantine built up and renamed after himself as Constantinople. That's why the Eastern Roman Empire--over which Justinian later ruled--often is referred to as the Byzantine Empire.  Today, Istanbul is the name of the city that was once Byzantium and then Constantinople.

i would say your answer is a)

sorry if im wrong