The conversation between human and AI assistant.
[|Human|] Categorize this sentence as belonging to either declarative, interrogative, imperative, exclamatory, or optative:
For how long will the sale last?
[|AI|] Interrogative.
[|Human|] 
Categorize this sentence as belonging to either declarative, interrogative, imperative, exclamatory, or optative:
For how long will the sale last?