All of the above options are correct regarding the preference of Kiev.
Step-by-step explanation:
The Rus were the federation of the early Slavic people and they were looking for a more strategic position to expand to than Novgorod so they had decided to move to the part of Kiev.
This was due to a host of reasons:
It indeed was closer to the great city of Constantinople making it better for trade and alliance with them.
It was Located on the Dnieper River it was better for trade in Scandinavia and Asia.
This provided a great backdrop for the empire.