Problem: What are the most important words?
a bolt of lightning striking a tree in a field
Answer: field, lightning, tree

Problem: What are the most important words?
all kind of fishes and aquarium
Answer: aquarium, fish, kind

Problem: What are the most important words?
young woman practicing yoga on a platform in water on the lake during misty sunrise in the morning .
Answer:
morning, platform, practice, sunrise, water