The sentence "Fluffy goose down helps make down jackets warm." is grammatically correct.
Here's why:
- Fluffy goose down is the subject (what the sentence is about).
- helps make is the verb phrase, telling what fluffy goose down does.
- down jackets is the object that is being affected.
- warm describes the state the jackets get because of the fluffy goose down.
So, the sentence correctly tells us that fluffy goose down makes jackets warm!