Shahad started packing her lunch after her friend did. This change is primarily influenced by what?

The correct answer is that Shahad's decision to start packing her lunch is primarily influenced by social influences. This term encompasses the various ways in which individuals are affected by their interactions and relationships with others. In Shahad's case, seeing her friend make a similar change serves as a powerful motivator. Social influences can manifest through behaviors that people observe in their peers, leading them to adopt similar practices to fit in or align with their social circles.

While peer pressure is related, it specifically refers to the pressure to conform to the expectations of one's peers. Here, it is more about the general observation and adoption of a behavior prompted by environmental norms and cues provided by a friend.

Other options like health trends and advertising pertain to broader societal or media influences rather than direct interpersonal interactions. Although these can play significant roles in shaping behavior, Shahad's action is more reflective of the immediate social context she is part of, indicating a direct link to social influences rather than external pressures or trends.