All of the following are true of environmental concerns of the twentieth century except that
(a) air pollution produces global warming.
(b) the extension of agricultural activity aids biodiversity.
(c) global warming poses the risk of a rise in sea levels.
(d) urbanization reduces biodiversity.
(e) population increase is the basis of many environmental problems.

Well, one of the statements above is not a "concern" but would, if true, be a positive factor: (B) the extension of agricultural activity aids biodiversity.

This is however not true, extension of agricultural activity actually is a problem for biodiversity, as it introduces fewer species in the place where before more species flourished. So this statement is false, and if true would not even be a concern.