Hold over vs. hold off

Hi,

Why is the choice 'be held off' wrong for Q4 in the test of http://www.usingenglish.com/members/...hp?quiz_id=444?

I thought hold over = hold off = postpone. Are they different here because of the usage?

Thank you.

Held over is correct. Put off would also be correct, but since the phrasal verb is 'hold...;-)