Question

Survival of at least a few members of a population after a major environmental change is most dependent on

1) the population having an individual that is adapted to the original environment 2) the population having an individual that is adapted to great changes in the temperature and its environment
3) variations in many different traits in many individuals in the population
4) no variations in the color of the fur, skin, or feathers of the individuals in the population

Answer 1

Survival of at least a few members of a population after a major environmental change is most dependent on 3) variations in many different traits in many individuals in the population.
Variation is important for a species which wants to survive huge changes in the environment. If they cannot adapt to their new surroundings, they won't be able to survive. This is where variation comes in - it enables a species to develop new techniques and traits necessary for survival.