Answer:
UNESCO
Explanation:
The United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Sites are places of importance to cultural or natural heritage as described in the UNESCO World Heritage Convention, established in 1972.
A spillway<span> is a structure used to provide the controlled release of flows from a </span>dam<span> or </span>levee<span> into a downstream area, typically being the river that was dammed. In the UK they may be known as </span>overflow channels<span>.</span>
Based on the situation, that was an example of : Free-Rider problems
Free-rider problems refer to a condition when an individual either consume more than the fair share or pay less than the fair share.
Hope this helps
A good example of a secondary source document useful in the study of history would be a textbook, because it provides basic information even though it wasn't an actual document from the historical time period.
