Answer:
A. The model of urban structure most often observed in megacities in developing countries is the concentric zone model, the sector model, and the multiple nuclei model. How the models are different is by having different shapes and different columns.
B. The two factors that lead to the growth of megacities in developing or least-developed countries is migration from rural areas, high fertility rates, and widening of the city's boundaries.
C. The two factors that led to the formation of squatter settlements in megacities in the developing countries is lack of jobs and expensive housing. Rural to Urban migration is very influential in most megacities settlements and this will lead to squatter settlements. Rural to Urban migration is very common in this part and the more the population the more pressure for the Government to build infrastructure for employment so in that process there will be lack of jobs and even for them to afford normal apartment will be difficult therefore it will lead to squatter settlement for them.
Sorry if it isn't complete