Answered


Books such as The Octopus by Frank Norris, How
the Other Half Lives by Jacob Riis, and The
Jungle by Upton Sinclair exposed problems
associated with
(1) naturalization of immigrants
(2) westward expansion
(3) rapid industrialization
(4) environmental conservation



Answer :

Books such as The Octopus by Frank Norris, How the Other Half Lives by Jacob Riis, and The Jungle by Upton Sinclair exposed problems associated with "(4) environmental conservation."