Why are experimental investigations the best type of scientific investigation to demonstrate cause-and-effect relationships?

What were the death camps? who was sent there?

Which of these describes a social effect of the civil war? a) fields were left unplanted because the slaves had been freed and much of the male population was unavailable to plant or harvest crops. b) over 600,000 men died, mostly because of the lack of food, clean water, and hygienic medical practices. c) after the emancipation proclamation was issued, african americans were allowed to join the union army. d) lincoln’s assassination after the surrender caused a disruption in the rebuilding of the nation.

Industrial life changed society in all of the following ways except a. eliminated the need for a poor, working class c. a middle class developed b. women joined the workforce d. society became urbanized