I believe rice became a Chinese Staple food during the Tang dynasty because new types of rice and new growing techniques yielded bigger harvests. Hope that helped.
For the answer to the question above, the purpose of this policy was to maintain neutrality between the United States and European countries while giving aid to Britain by allowing them to buy non-war materials. So my answer is B. <span>were designed to supply Great Britain and other Allied nations with war materiel.
I hope this helps</span>
