Concept:
Selection of teaching media depends on visibility, interaction level, and scalability with class size.
Step 1: Small class (2–3 students):
Personalized instruction is best done using writing on paper for direct explanation.
Step 2: Medium class (10–15 students):
A flip chart or whiteboard ensures visibility and interaction.
Step 3: Large class (20–25 students):
PowerPoint slides provide structured visual clarity.
Step 4: Extra-large class (>30 students):
A display screen ensures visibility for large audiences.
Conclusion:
Thus correct matching is a-IV, b-I, c-II, d-III.