From Statement(1) ALONE we can deduce that 3000/4=750 wool jackets but we are DO NOT KNOW if the remaining 250 jackets can be manufactured by the 2000 pounds of cotton.(Irrespective of if the manufacturer intends to make cotton only jackets. So the answer to the question stem can be YES/NO.(Thus, insufficient) 


From Statement(2) ALONE we can deduce that 333 cotton jackets can be manufactured but we DO NOT KNOW if the remaining 667 jackets can be manufactured by the 3000 pounds of wool. 

So the answer to the question stem can be YES/NO.(Thus, insufficient)


Combining Both we have 750+333=1033 jackets can be manufactured and we get a YES answer to the question stem.


Hence answer option (C) as we need both statements to answer the question stem.