Cynthia tells darryl that she will deliver his boxes of paradise cookies as he directs. a declaration that one will do something in the future is part of the definition of

The answer is "a promise". A declaration that one will do something in the future is part of the definition of making a promise. In the given sentence, Cynthia promises Darryl that she will be delivering his boxes of paradise cookies as he directs. Which is why the sentence is in a form of making a promise.

The answer to make the statement or sentence complete is "a promise". Cynthia is making a promise to darryl that she will deliver his boxes of paradise cookies as he directs and when someone is declaring that one will do something in the future.