I believe the answer is extended examples. 
I have two reasons for saying that. 
1. I’ve learned from experience, extended examples are highly effective in many ways. 
2. I think I have answered this question for someone else or on one of my own exams. Your choices are most likely:
•peer testimony 
• statistics 
•visual aids 
•brief examples 
•or the correct answer, extended examples. 
I hope I have been successful in assisting you. Please let me know if you have further questions!
~Brooke❤️