Social-cognitive theorists: a. suggest that people can modify and create their environments.
b. primarily emphasize environmental influences and the learning of habits through repetition.
c. primarily emphasize environmental influences and the learning of habits through reinforcement
d. suggest that people cannot engage in intentional learning

answer; i believe the correct answer is (4) flip a coin as each participant arrives,heads indicates assignment to the first group: tails indicates assignment to the second group;

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.

answer; a serious and pervasive issue for many people;

answerlittle bighorn,1876