Answer:
The correct answer is Salient.
Explanation:
In neuropsychology, and stimuli that is salient stands out from least salient items. The more salience and item has the more probable it will capture attention from the individual perceiving it.
In this particular case, to Heather, the more memorable stimuli were the balloons and bubbles and she didn't remember any of the safety rules the officer talked about. Heather obviously paid more attention to what was Salient.