Rome was not a good place for the capital because it was difficult to manage all the regions, and to defend against the barbarian invasions. So, for question number 3, the right answer is a, because Constantinople had a better strategic position and could stop the barbarian invasions.
For question number 4, the Byzantine empire kept using the Roman law system, but it had a Christian influenced.
For question number 5, the Eastern Roman Empire had many major achievements, but of the greatest is the arrangement of Roman law in an orderly form. The Roman law was codified by Justinian I in the 6th century and it’s known as the Justinian’s legal code. This legal code has been used as the base of multiple Western countries' legal codes and it’s still relevant nowadays.
