Self-study
The conventional process for tanning leather uses large amounts of calcium oxide and sodium sulfide. ███████ ███████ █████ ██████████ █████████ █████ █████ ███ ████ ██ █████ █████ ████████████ █████████ ██ ███ ████ ██ █████ ████████ ██ ████ ███ ██ ███ ███████████ ████████ ██████ ██ ███████ ████ █████ ██ ████████ ████ ██████████ ██████████ ███ █████ ████████ ██ █ ███████████ ████ ██ ███ ███████ ████ ██ ████████ ██ ██ █████████ ████ ██████ ██ ███ ███████ ██ ██████████ █████████ ███ ████ ████████
Summary
The author concludes that it is cheaper to tan leather using biological catalysts when compared to the conventional method. This is because the costs are the same for both methods outside of waste disposal, and less waste is produced when using the biological catalysts.
Notable Assumptions
The author assumes that it is not much more expensive to dispose of waste from the biological catalysts than it is to dispose of waste from the conventional method. Even if less waste is produced from the biological catalysts, it might cost so much more to dispose of it that any savings are completely offset, so the author must assume this in order for the argument to be true.
19.
Which one of the following ██ ██ ██████████ ████████ ██ ███ █████████
a
Leather tanned using ███ ████████████ ███████ ██ ███ █████ ██ ███████ ████ ██ ███████ ██████ █████ ██████████ ██████████
The quality of the leather is irrelevant to the argument. We only care about how much each method costs.
b
The biological catalysts ████ ███ ██ ████ ██ ███ ███████ ███████ ███ ████ ██████ ██ ██████ ████ ███ ███████ █████ ███ ██████ ████████
Like (E), we already know the overall costs outside of waste disposal are roughly even for both methods, so any discussion of the costs of other parts of the process is irrelevant. Even if some aspect of tanning is more expensive for one method or the other, the costs will always be roughly equal when ignoring waste removal.
c
New technological innovations ████ ████████ ████ ███ ███ ██ ██████████ █████████ ██ ███ ███████ ███████ ████ ████ ████ ██████████
(C) provides a potential reason why the costs outside of waste removal are similar for the two methods, but we don’t need this information. It could be because of new tech, cheaper materials, or government subsidies without affecting the argument.
d
Disposal of tanning █████ ████████ ████ ██████████ █████████ ████ ███ ████ █████████████ ████ ████ ████████ ██ ███ ████ ██████ ██ █████ ████████ ████ ███ ████████████ ████████
If (D) is not true—if disposing of biological waste costs way more than normal waste—then it doesn’t matter that less waste is produced. Biological waste removal would cost more overall, and the biological process would thus be more expensive.
e
The labor costs ██████████ ████ ███████ ███████ █████ ██████████ █████████ ███ ███ ███ ███████ ████ ███ █████ █████ ██████████ ████ ███ ████████████ ███████ ████████
Like (B), we already know that the overall costs outside of waste disposal are roughly even for both methods, so any discussion of the costs of other parts of the process is irrelevant. Even if some aspect of tanning is more expensive for one method or the other, the costs will always be roughly equal when ignoring waste removal.