When Must Form 8-K Be Filed with the SEC

When must Form 8-K be filed with the SEC?

A) within forty-five days of the end of any quarter other than the fourth quarter of the fiscal year.
B) within ninety days of the end of the fiscal year.
C) within fifteen days of the occurrence of certain significant events.
D) within sixty days of the end of the fiscal year.
E) when a relatively small company intends to issue securities.