What new weapon made allied leaders worry about the cost of invading the japanese mainland? kamikaze fighters machine guns atomic bombs warplanes

A Kamikaze fighter.

All other options were either not available to the Japs or already existed pre-war.

most people now work in jobs where they do one  kind  of work; they are carpenters, bankers, cooks, mechanics, and so forth. likewise, most  businesses produce  only certainkinds  of  goods  or  services, such as cars, tacos, or gardening  services. this feature of  production  is known as specialization.

i think it’s will be a yes