country a had a population of 1,000, of whom 600 worked an average of 8 hours a day and had a productivity of 2.5. country b had a population of 800, of whom 560 worked 8 hours a day and had productivity of 3.0.

answer; the basal forebrain;

explanation:

allergens: overstimulate the nerve system

neurotics: attack nerve cells

mutagens: damage or otherwise alter dna sequence

generators: cause defects during growth and development  

carcinogens: cause unchecked cell growth

i hope you get the idea according to me these are the effects that happened.

fertile good for trade etc