The African continent isn't suffering from the environmental challenge "reforestation", since most of the continent hasn't suffered deforestation.
1. <span>the process started with the collapse of a nebula
The universe almost certainly didn't start from the collapse of a nebula.
2. The mantle is the middle layer.</span>
LEDC means that a country is a developing country (as opposed to a developed country). This distinction is connected to the Brandt line which divides the world into developed and developing country, and India is south of this line (=LEDC, less developed country). Some reasons for this is malnutrition, high child mortality and short life expectancy.
Gypsum is a chemical sedimentary rock.
