Self-paced
Scientists have recently discovered that, in doses massive enough to kill cells, almost any chemical is carcinogenic because cell death causes rapid division among surviving cells, promoting cancer-causing mutations. █ ███ █████████ ███ ████ ████████████ ███████ ███████ ████ ██████ █████ ███ ███████ ██ ███ ███████████████ ██ ████ █████████ ████ ██████ ████████ █████████████ ██ ████ ███████ █████ ██ █████████ ██████ ████ ███ ███████ ████████ █████ ████████ ██████ ███ ███████ ██████ ██ ████ █████ ███████ ██ █████ ██ ███ ████████ ███ ████ █████████ ███ ██████████ ██████ ██████
Stimulus Breakdown
The stimulus gives us a bunch of information about the carcinogenicity of chemicals. This is what we learn about carcinogenicity in general:
(1) if given in cell-killing doses, almost all chemicals are carcinogenic;
(2) this is because cell death leads to rapid cell division and mutation;
(3) some chemicals are carcinogenic even without causing cell death.
The stimulus then describes the traditional method of studying food additives, to determine if they're carcinogenic, using test animals. These studies use a dose higher than humans would ever be exposed to, which is high enough to kill lots of cells. Researchers then observe the resulting cancer rates.
But wait—based on the facts given, it seems like this procedure would almost always observe higher cancer rates, regardless of the chemical studied. After all, they're giving cell-killing doses, which are almost always carcinogenic. We can look for this conclusion in the answer choices, then turn to POE if needed.
16.
If the statements above are █████ █████ ███ ██ ███ █████████ ███████████ ██ ████ ████████ █████████ ██ █████
a
In the doses ██████████ ████ ██ ███████████████ ███████ ██ ████ ██████████ ████ █████ █████ ████ ███ █████ ██ ████ ████████
The stimulus describes the current procedure as being used "until now." That might somewhat imply that a new procedure will be used in future, but even if so, it doesn't tell us any details of a new procedure. (A) is an unwarranted assumption, not a strongly supported conclusion.
b
Until now results ██ ███████████████ ███████ ██████████ ██████████████ ██ ███ ██████ ██ █████ ████ ████ █████████ ███ █████████████
Carcinogenicity studies administer higher doses than humans would ever encounter, at levels that kill lots of cells. But almost all chemicals are carcinogenic at such levels, just due to the effects of cell death. That means these studies weren't representative of carcinogenicity in human conditions, and were likely to find more chemicals carcinogenic.
c
Truly carcinogenic chemicals ███████ █████ ████ █████████ ████ ██████ ████ ██ █████ ██████
What does "truly carcinogenic" mean? We know there are some chemicals which are carcinogenic even in doses too low to cause cell death. But by definition, those chemicals don't cause cell death. The stimulus doesn't support any particular definition of "true" carcinogens, let alone (C)'s definition.
d
Carcinogenic chemicals are ███████ ████████ ██ █████ █████ ██ ███ ███████ ████████████
The argument isn't concerned with the natural environment. The only context it discusses where carcinogenic chemicals might be encountered is in food additives. And even then, we don't know how big or small the usual doses are, just that lab animals are given much higher-than-usual doses.
e
Most of the ████ █████████ ████ ███ ███ ██████ ███████ ██ ███████████████ █████ ██████ ██ ████ ██ █████ ██████
The stimulus suggests that current testing procedures are likely to find more chemicals carcinogenic than would actually be carcinogenic in human foods. But that's just an overall procedural bias. We don't know how many banned chemicals would in fact be safe, let alone that "most" of them would.