The answer is C. Law of original horizontality.
sedimentary layers are laid down horizontally when they're initially deposited.
The correct answer is - industry.
The developing countries are most often occupied with making the economies heavily focused on the industry, so the countries engage into a big industrialization process.
The industries are usually based around manufacturing of the natural resources that the country has, and most often those are the metal ores, the agricultural products, creating materials...
The developing countries usually have a relatively big economic growth, and that is due to the bad economic basis that they had as a starting point.
Even though it is slums we are talking about, and we know how terrible the conditions are, still there's always some surprises (negative ones unfortunately). Specifically in Mumbai, it is surprising that big portion of the people living in the slums do not have access to city services, they do not have enough water even thought the city itself is surrounded by water, more then half of the population of Mumbai lives in slums (around 55%), most of the residents do not have toilets and have to pay for public toilets...
