Why was the concern over global cooling replaced with a concern over global warming?
a. The science community needed a cause to frighten the general population.
b. Steady surface temperature increases were noted between the 1970's and 90's.
c. Air pollution only became a concern in the 1980's.
d. Scientists observed severe ocean acidification.

answer; ///(a) ;

the right option is; decreased genetic variation  

decreased genetic variation describes the effect of this environmental change.

genetic variation is the naturally occurring genetic diversities or differences between organisms of the same species in a population. genetic variation allows the survival and adaptability of a species when they encounter changing environmental conditions. when an endangered species reduces, it loses genetic variation which may not be restored even if the species rebound and will only be recovered through the gradual collection of mutations over many years.

unless you remeber everything you always have to have data when recording anything.