What are some ways to stop genocide? like the holocaust

Aclaim about history is most likely not valid if it has which of these characteristics?

Plz ! after the first battle of bull run general ivan mc dowell was removed from command of the union army he was replaced by a. general ulysses s. grant. b. general george mcclellan. c. general robert e lee. d. general george meade.

Explain how stock market speculation contributed to the great depression.