The water flowing in a stream or river is fed by numerous smaller streams, which are fed by even smaller streams that collect water from melting snow or ice up in the mountains, from springs, and possibly from human wasterwater sources. The bottoms of rivers are also below the water table in many places, so there will always be water at that level.
The answer is D. In caste systems you are born into a certain level of society and cannot change that.
The answer is true.
If the water wasn't clean most would be sick.
It states that rocks closer to the top are newest.
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.