The Window of Opportunity for Policy Change Stays Open for a Limited

The window of opportunity for policy change stays open for a limited amount of time because…

A) public attention eventually moves elsewhere.
B) the problem may be solved.
C) realization dawns that the problem is complex.
D) All of the above are reasons why the window of opportunity for policy change stays open for a limited amount of time.
E) None of the above are reasons why the window of opportunity for policy change stays open for a limited amount time.