Answer:
Heidi changing her hairstyle based on a picture in a magazine.
Step-by-step explanation:
Informational social influence describes the change of behavior one makes due to information about social norms of others. Hence, the only change that is made due to information (like magazines, books or social media) is Heidi changing her hairstyle based on a magazine, and her actions show informational social influence in action.
Hope this helped!