There were three Nebuchadnezzar's who reigned. Assuming that you are talking about Nebuchadnezzar I, he reigned during 1125 - 1104 BC.
The following are correct:
A moat filled with water from the Euphrates River surrounded the city.
Walls around the city provided protection from enemies.
Answer: i really have no clue but if i put this i get points so good luck on your test