21 Read the story below Select the best answer for the following item Our use of enormous quantities of natural resources has caused much anxiety about the future As our population grows our resources are being exhausted at an increasing rate When our nation was young and had a small population we thought our resources would last forever With a small population labor was scarce and people did not bother to prevent waste By 1900 our vast forests were three fourths gone Today our coastal fishing grounds are producing less than before and much farmland has been lost to erosion Most of our large cities are concerned about the problems of water supply and many of our smaller cities are looking for additional water Fortunately interested citizens scientists and government officials have become increasingly aware of our diminishing resources and are studying ways of saving them Proper conservation however does more than protect resources for the future it also increases their present production The wise conservationist wants to use resources to provide for future generations as well as for our own Wise use means no waste Conservationists urge that we manage our living resources to balance their consumption with the growth of a new supply Whether it is trees grass or fish no more should be used than can be replaced by normal growth Minerals a funded resource cannot replace themselves Conservationists therefore advocate cautious use of them Scrap metal for example should be melted down and used over again Whenever possible the more plentiful minerals should be used in place of the scarce ones With efficient use of our resources we can meet our present needs and also provide for the future 6 37 38 ac D According to this article conservationists include city councils O concerned citizens