Danielle, a college senior, is trying to remember the names of the classmates that attended her high school graduation party but cannot. it is most likely that

The answer is "she has not yet found the cues that will help her retrieve the information from long-term memory."

A long term memory is anything you recollect that happened in excess of a couple of minutes prior. 
Long-term memories aren't all of equivalent quality. Stronger memories empower you to review an occasion, technique, or certainty on request. Weaker recollections frequently ring a bell just through provoking or reminding.