As the difference among  computer manufacturers in the areas of price and performance narrows, support for green computing is emerging as a new business strategy for these companies to distinguish themselves from the competition.

To determine the difference between two Instants, use class Duration’s static method ________, which returns a Duration object containing the time difference.

a. difference b. interval c. between d. span

Keyword ____________ introduces a structure declaration.

Fill in the blank(s) with the appropriate word(s).