Hmmm how? By asking a question or
Answer:
participates
Explanation:
if she takes part in it every time then it becomes ' participates' but if only once it could have been 'has participated'
I would say the main headings and key concepts in a reading assignment would help one to grasp what the topic is basically about ie paying attention to these two things would be an essential part of a study guide so that the main meaning of the writing could be grasped.
I think it is D.
'It' makes the sentence unclear in purpose