The correct answer is - a. having differences.
The term heterogeneous is a term used to describe something that is different, that is not the same, or that there's multiple different things. This term can be used for various different things, including human societies, geography, biodiversity, etc.
In the human society, heterogeneous, is used as term when there's societies where multiple different ethnic groups live in a same area, or different racial groups, it may also be used in a manner of representation of the sexes in a particular filed or job, even the architecture and the infrastructure.
Answer:
Option (A)
Explanation:
In the above-given question,
Option (B) is wrong with it's usage of the modifier "how'' in the sentence. If the modifier is used in one place (how heat from the inner core flows), it should also be used in the continuing clause (how the formation and periodic reversal).
Options (C) and (D) are wrong in using the word "are" for the whole sentence as there is no need to use this word. The verb form will depend on the subject, in this case, is "the discovery that earth's inner core" which is singular in nature. Thus, the verb form will be -is and not -are.
Option (E) is wrong for it's use of the comma. If the comma is used, then the whole sentence is not a full-fledged sentence but rather a dependent clause with no resolution.
The correct answer for the given passage is option (A).
I think what is soviet union or germany