Why is planting a wide variety of plant species better than planting only one type? A)
Diversity is best for the environment.
B)
A wide variety would mean less wear and tear on the soil.
C)
It would lead to desertification prevention.
D)
Combining biological and chemical controls are the conditions of a healthy farm.

A. describe the model of urban structure most often observed in mega-cities in developing countries. explain how this model differs from common urban structures in north america. b. describe at least two factors leading to the growth of mega-cities in developing or least-developed countries. c. identify and explain two factors that led to the formation of squatter settlements in mega-cities in developing countries.