Thanks for the follow up!
"In which" (as used in the answer choices to #1 on page 222 of the Logical Reasoning Bible, and generally elsewhere) simply provides a specific quality or characteristic possessed by something else. In this case it's a feature attributed to a (any) "nation." So it's a modifier intro, not a sufficient or necessary indicator.
Here's what I mean.
In the example given, answer choice (A) is, roughly, "Any nation in which consumer confidence is balanced...will experience growth." The indicators there are "Any," which sets up the sufficient, and "will" which gives the necessary. "In which" tells you
about the sufficient, but doesn't
make it sufficient.
Other words like "with" or "in" or "where" (and many, many more) could function similarly. Typically we call these
prepositions.
Any car
with an electric engine will experience battery drain.
Any person
in Siberia will experience frigid winters.
Any major city
where smog is unregulated will experience the occasional hazy day.
These words as used above just introduce modifying, or qualifying, clauses (often prepositional phrases), but have no impact on conditional function, sufficient or necessary.
Here's "in which" modifying some necessary conditions, for example:
Ants require an environment in which food is readily accessible.
You will have ant problems only if you have a house in which food is left out in the open.
Those are silly, made up examples, but they show you the variability of the term in question
I hope that helps!
