What is productivity?

Between the world wars eisenhower's presidency the 1960s what is the organizing principle of this list?

Which statement best describes the underground railroad? a.) it is a train that took slaves from the south to the north. b.) it is a business that harriet tubman founded to slaves become free. c.) it is a secret route that slaves took to escape from southern slave states to the north. d.) it is a road that slave owners disliked using for travel.

Select the correct answer. in what type of immunity will the defenses be triggered and react in the same manner, regardless of the organism invading? a. adaptive b. innate c. primary d. mechanical barrier