Answer: A. transition from a meadow to a forest
Transition from a meadow to a forest is the correct environmental change that would likely to allow the most individuals to survive because meadow is grassland which may be occupied with organisms with low trophic levels such as primary producers like grasses, primary consumers like herbivorous insects and animals. But forests involves the diversity of trophic levels like primary producers like trees, primary consumers like herbivores such as rabbit, deer, secondary consumers like snakes, fox and tertiary consumers like lion and tigers. Hence, forest environment will allow the growth of diversity of life forms.