Certain gemstones are formed by magma, a material found deep inside the Earth, that has pushed toward the surface and solidified; others are created when superheated water and gases cool. When chemical action, heat, or pressure changes the existing structure of rocks, they may recrystallize to form gemstones such as emeralds. A large chemical company plans to create a new source of profits by applying certain of the chemicals it manufactures to specifically chosen rock samples, which would be a much less expensive way to produce emeralds than mining them.
which one of the following, if true, poses the most serious problem for the success of the company’s
plan?
A. Man-made emeralds will not be considered as valuable as naturally produced emeralds.
B. Natural emeralds are produced by heat and pressure much more frequently than by chemical action.
C. The types of material from which emeralds are formed are not found on the Earth’s surface.
D. Laboratory conditions are difficult to replicate in a large-scale factory.
E. The gases that will mix with superheated water are so toxic that workers could suffer from a number of serious medical conditions if the handling of such gases is not strictly controlled.