Which layer of the earth is composed of iron and nickel, and has two main parts called the outer and the inner ?
a. the mantle
c. the crust
b. the core
d. the lithosphere

The Crust and Lithosphere (which are almost synonymous) are not typically divided into two distinctive layers, so we can reject them.

The correct answer is is the core: (b). The inner core is solid and it's made of iron and nickel. The outer layer is liquid and this is the reason for the differentiation of the two parts. 

Aregion is an area of land that has common features. these features can be natural, such as climate or landscape. they can also be artificial, such as language or religion. the xinjiang uyghur autonomous region, above, is an area of china inhabited by uyghurs, a muslim group with ethnic ties to turkish people.