The main reasons for America's economic boom in the 1920s were technological progress which led to the mass production of goods, the electrification of America, new mass marketing techniques, the availability of cheap credit and increased employment which, in turn, created a huge amount of consumers.
I know it had something to do with the Indian. look up Punjab region.
Answer:
The "grave danger" that the author is talking about is the danger of atomic weaponry
Explanation:
"Preliminary Statement of the Association of Manhattan District Scientists" was a 100-page report written after the atomic bombings in Hiroshima and Nagasaki.
The "grave danger" that the scientist is talking about in the article is the dangers of atomic weaponry. The article talks about the consequences that wrong decisions of leaders may have on its nations.
Your answer is:
weak rulers known as "do-nothing-kings"
Hope this helps!!
(Brainliest)