ilovemydog,
Thanks for the question. This is a
really tricky question - it actually tests something called formal logic, which basically means our regular necessary and sufficient conditional reasoning PLUS an added element of certainty/uncertainty involved (i.e., we see the word "many" in comparison to "all" and "none"). But I think despite this, we can attack this as a traditional conditional reasoning problem with our logic chains. Here's how I have it diagrammed:
All highly successful salespersons are both well organized and self-motivated =
HS WO + SM
Only those who are highly successful are well known among their peers =
WKAP HS
No salespersons who are self-motivated regret their career choices =
RCC SM
(This one is a little tricky, but I turned it into the if-then statement "if a salesperson regrets his/her career choice, then he/she is not self-motivated")
Now we can be free to go through the answer choices, looking for ways to chain these statements together to make one of them true (this being a Must Be True question).
(A) No self-motivated salespersons who are not highly successful are well organized. - This represents a mistaken reversal of the first chain of reasoning. Taking away all of the double negatives here, this basically means that if a salesperson is self motivated and well-organized, then she MUST be highly successful. But all that means is that she has the necessary attributes of a highly successful salesperson; we don't know that all people who are self motivated and well-organized are highly successful (we only know that if a person lacks one of those traits, then she can't be highly successful).
(B) All salespersons who are well organized but not highly successful are self-motivated. - We don't know that this is true, in fact, if a salesperson is well organized and self motivated, then they could be highly successful (those are our necessary indicators for highly successful).
(C) No salespersons who are well known among their peers regret their career choices. -
This is the credited answer. To get there, we need to use the contrapositive of the last statement, which would read "If a person is self motivated, she does not regret her career choices" and would diagram: SM
RCC. Once we have that, we can chain our conditional reasoning (with that at the end) to this: WKAP
HS
SM + WO
RCC. The logic of this is sound, making it our credited answer.
(D) All salespersons who are not well organized regret their career choices. - We know that if a salesperson isn't well-organized, then she isn't highly successful. But there's no way to chain that with the regretting career choices conditional reasoning, and so this answer choice can't be correct.
(E) All salespersons who do not regret their career choices are highly successful. - If we take the contrapositive of the final statement, we have SM -
RCC. So we know that self-motivated salespeople are the ones who don't regret their career choices - but we don't know if any (let alone all) of these same salespeople have the other necessary condition (being well-organized) to make them highly successful. Therefore, this answer choice is incorrect.
Hope all of this helps!
Alex