The answer in the space provided is experiments. It is because in order to produce causation or to likely have a cause of something in particular, they need to conduct experiments in which they will likely form new ideas and test this ideas to form something new that will cause and contribute to others and will be of gain of knowledge.
Answer:
Phycologist in every subfield draw on and contribute to knowledge from other subfields.
Answer:
He believed that slavery would either become completely legal, or completely illegal, as the nation couldn't survive divided as it was. So, the second option.
