What was the advantage that Cordell Hull had during his meetings with Kichisaburo Nomura? I - He was able to read Tokyo's instructions to the amba...

What was the advantage that Cordell Hull had during his meetings with Kichisaburo Nomura?

I - He was able to read Tokyo's instructions to the ambassador before the meetings.
II - He was able to read Nomura's reports after the meetings.
III - He was able to read the top-secret Japanese diplomatic code.
IV - He played his part adroitly, never giving any hint of knowing more than he was supposed to know.
a) Only I and II are correct.
b) Only II and III are correct.
c) Only III and IV are correct.
d) I, II, and IV are correct.
e) I, II, III, and IV are correct.