At first while going through the questions for this passage, I confused "cultivated" with "processed." Then I realized that the former is used twice: 1) to refer to the "cultivated maize" grown by the Zuni, who are presented as an example in support of the general rule that agricultural populations had higher rates of caries; 2) to describe the "hunter-gatherer-cultivator" economy of the Ban Chiang population, who "became increasingly dependent on agriculture" over time and whose diet "included some cultivated rice and yams from the beginning." So we can associate "cultivation" with "agriculture." Meanwhile, the only time we hear about processed foods is in reference to the "highly processed stone-ground flour made from gathered acorns" by the populations in western North America, who are held up as an exception to the general rule because they were nonagricultural populations. So processed foods can be a part of a nonagricultural population's diet, while cultivation specifically refers to agricultural methods. Understanding this distinction is important when it comes to Question 18.

I had problems with this Q and identified 2 missteps as part of my problem. 1) was my reading of the stimulus, and 2) was my reading of the correct answer choice.

1) In the stimulus, it says, "For ANY social system, the introduction of labor-saving technology that makes certain economic roles obsolete will tend to undermine the values in that social system." The sufficient condition is labor-saving technology that makes certain economic roles obsolete. If technology is introduced that eliminates economic roles, it will tend to undermine the society's values. The stimulus says this relationship is true of any society. But it does not say that labor-saving tech can have this effect of eliminating economic roles in any society. Maybe there are some societies whose economic roles are immune to being rendered obsolete by labor-saving technology. If, for some reason, there's a society in which labor-saving technology can't make any economic roles obsolete, then the sufficient condition is not fulfilled, and that society's values don't have to be undermined/changed.

Because I missed this aspect of the sufficient-necessary relationship, I read C as being directly contradictory to the passage, since I thought technology had to have this effect in any society, period.

2) Like JordanAngelina below, I read answer choice C as saying, "The introduction of new technologies would not have the capacity to eliminate economic roles in a society whose values aren't susceptible to change." This reading subverts the actual structure of the sentence, which says, "A social system whose values are not susceptible to change" [sufficient condition] "would not be one in which technology can eliminate economic roles" [necessary condition].

In C we're asked to presume there's a hypothetical society whose values aren't susceptible to change. So we start with values change → and the rest of the sentence fills in the other side of the arrow: values change → labor-saving tech that eliminates economic roles — the contrapositive of the sufficient-necessary relationship originally laid out in the stimulus.

Hope this helps someone else!

Interested!