This argument can be written as condition statements, the hallmark of LSAT formal logic.
If rich, then not poor AND If poor, then not rich
If not rich, then poor AND If not poor, then not rich
If honest, then not dishonest AND If dishonest, then not honest
If not honest, then dishonest AND If not dishonest, then honest
If poor farmer, then honest AND If not honest , then not poor farmer
Substitute terms: If dishonest, then rich farmer
The author then concludes:
If rich farmer, then dishonest
You can see this is the reverse of the final premise after we substituted terms. So the author is assuming biconditionality (x if and only if y). The first two premises are already biconditional, so we can expect the reverse of some form of the final premise in the answers.
The correct answer is the reverse of the unaltered form of the last premise.
You really won't find questions this immersed in formal logic on the GMAT, so I wouldn't recommend laboring over these ideas, however they are interesting.
