Why did Rockereller testify in 1919?

Which of these resulted in an actual slow down or limiting of the u.s. and soviet nuclear arsenals?

Which of these effects of mass production techniques used during 1920

How are the republican and democratic presidential candidates chosen? a. they are nominated by their state governments. b. each is nominated by his or her respective party. c. each is chosen by the governor of his or her home state. d. they are chosen by the house of representatives.