Answer: dolomite rock that becomes soluble over time
Explanation: ageing infrastructure that combined with volatile climate that are major causes of the appearance of the sinkholes
It covers around 1,200,000 square miles.
https://www.britannica.com/place/West-Siberian-Plain
Hope this helps, if not then I’m sorry
The statement is correct.
When a flood is giving a time-bonding term, such as the 100-year flood, in this statement, it means that it has been noticed that the floods from the particular river occur on approximately that much of a time span.
If there has been a flood recently, than it most probably means that there isn't going to be a flooding caused by that river for the foreseeable future.
Now, there's always exceptions, as the climate patters are changing constantly, and there's always surprises, but in general, in lot of regions of the world, there has been noticed a certain consistency in some natural occurrences.
The innermost layer or the lower most layer of the Sun's atmosphere is called the photosphere. It is the visible surface of the sun that we are most familiar with. The sun is a ball of gas; however, the solid shape we see is actually just a layer which is about 100 km thick. The correct answer to this question is letter "C. Photosphere".