Marina has struggled with exams all semester. She has started to worry that she has memory problems, but her roommate points out that Marina checks email, texts, and listens to music while studying. In other words, Marina's real problem isn't memory but .

Attention

Explanation:

  According to the given scenario, The marina's real problem about not concentrating on her exams is the lack of attention and is not the problem with the memory as while studying she used to access her mobile phone and also listening music.  

 So, the the major problem is due to the lack of attention as it is one of the major issue which is associated with the less attentive nature due to the different types of circumstances or situations.

 In this type of situation, the student are not attentive in the learning process and miscellaneous doing other works and things such as texting, check out emails and listening music. Therefore, Attention is the correct answer.

answer; shared meaning;