It might be helpful, on a parallel reasoning question like this, to replace the terms with abstractions, such as letters or numbers, to help keep the elements straight as you compare to the answer choices.
So from the stimulus:
Every moral action is the keeping of an agreement, and keeping an agreement is nothing more than an act of securing mutual benefit.
MA
KA
SMB
1
2
3
Clearly, however, not all instances of agreement-keeping are moral actions.
This statement is merely acknowledging the flaw in doing a Mistaken Reversal of our first statement: It is
invalid to state that KA
MA, or that 2
1
Therefore, some acts of securing mutual benefit are not moral actions.
This is an acknowledgment that we can have a necessary condition -- securing mutual benefit -- without having one of our sufficient conditions that was to the left of it. In other words, MA
SMB, or 1
3, but NOT SMB
MA or 3
1.
Getting down to distinguishing between D and E:
D states "All architecture is design and all design is art. However, not all design is architecture. Therefore, some art is not design."
First statement: Arch
design
art, or 1
2
3 Looks good so far, just like our stimulus.
Second statment: It is invalid to state that design
arch, or that 2
1. Still tracking our stimulus.
Conclusion: Invalid to state that art
design, or that 3
2 -- Aha! we've strayed from the stimulus, whose conclusion related elements 3 and 1, not elements 3 and 2. This makes D incorrect.
E states All books are texts, and all texts are documents. However, not all texts are books. Therefore, some documents are not books.
First statement: Book
Text
document. 1
2
3
Second statement: Invalid to state that texts
books, invalid to say 2
1
Conclusion: Invalid to state that 3
1, just like our stimulus!
I hope that is helpful.
Best,
Dan
