As you may know, trees are used to make things like furniture, cottages and paper. Unused paper is then 'thrown in the recycling bin' and recycled (go through the same system to be reused). Deciduous tree leaves specifically, fall off in Autumn so the sticks, trunk, and remains of the tree can be used to make products with the nutrients in the wood. I think this is part of an ecosystem - hope I help! :D
B) India has an especially high overall population. It's right after China when it comes to population, and it has over a billion people. Using a little math, even if you have a large Muslim population but over a billion people in your country, the percent of Indian Muslims will be small.
Levees and embankments allow humans to c)settle below river level. A levee is defined as "an elongated naturally occurring ridge or artificially constructed fill or wall, which regulates water levels." This definition can also be used for the term embankment.
The answer is C. Savanna. Good luck!