Which movement promoted the concept of "survival of the fittest" as an explanation and defense for the behavior of robber barons? Social Darwinism
the Progressive Movement
the Settlement Movement
the Social Gospel Movement

it's social darwinism

Explanation:

Social Darwinists held that the life of humans in society was a struggle for existence ruled by “survival of the fittest,” a phrase proposed by the British philosopher and scientist Herbert Spencer.

to act quickly in times of danger to the united states

because you have to act quickly if you want to live/survive.

cutting down of the rainforest