Traditionally, decision-making by managers that is reasoned step-by-step has been considered preferable to intuitive decision-making. However, a recent study found that top managers used intuition significantly more than did most middle- or lower-level managers. This confirms the alternative view that intuition is actually more effective than careful, methodical reasoning.
The conclusion above is based on which of the following assumptions?
(A) Methodical, step-by-step reasoning is inappropriate for making many real-life management decisions.
(B) Top managers have the ability to use either intuitive reasoning or methodical, step-by-step reasoning in making decisions.
(C) The decisions made by middle- and lower-level managers can be made as easily by using methodical reasoning as by using intuitive reasoning.
(D) Top managers use intuitive reasoning in making the majority of their decisions.
(E) Top managers are more effective at decision-making than middle- or lower-level managers.

Can someone explain it to me that why the correct is not B
Source:GMAT prep.

first, realize what's essential to the argument and what isn't.
the sentence starting with "traditionally..." is NOT an integral part of the argument in any way; it merely serves as a foil, or counter-premise, against which the argument is built. in other words, it's a "bowling pin": it's set up precisely so that the argument can knock it down.

therefore, the entire argument can be summed up as follows:

top managers use intuition more than do midlevel or lower-level managers
-->
intuition is MORE EFFECTIVE

there's a huge, glaring hole there: the argument has connected "top managers do it more" with "it's more effective". these 2 specifics are entirely different from one another, and NEED to be bridged ("fill in the logic gap", if you've taken our course) for the argument to hold up.
in fact, you should get into the habit of regarding ANY two specifics that are even remotely different (such as "drivers who speed" and "drivers who receive speeding tickets") as completely different things. under that criterion, it's a no-brainer to choose the assumption that bridges the gap.

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as for why (b) is incorrect:
i can see the appeal of choice (b), but it's not necessary.
it's very possible that you may have misread the following statement:
top managers used intuition significantly more than did most middle- or lower-level managers
as saying this:
top managers used intuition significantly more than they used methodical reasoning (WRONG INTERPRETATION).

that's not what it says.

it just says that the top managers used intuition more than did other managers. this is perfectly consistent with a scenario in which top managers can choose between intuitive and methodical reasoning, but, unfortunately, it's also perfectly consistent with a situation in which top managers have to use intuition 100% of the time and don't have any other choice. thus, choice (b) is incorrect.

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analogy:
top jai-alai players all play right-handed. therefore, right-handed play is more effective than left-handed play.
note that this does require the assumption that top players play more effectively. it does not require the assumption that those players can choose between playing right-handed and playing left-handed (indeed, they almost certainly can't, as handedness isn't a choice).

Thank very much for your help. :D

HI

IS OA : E

Yes. And notice that that's an assumption many of us are likely to make as well (call it the mystique of authority).

my question is why is [spoiler]b [/spoiler] wrong..
The top managers just dont know how to use methodical reasoning and hence they use intuitive reasoning....

please read the thread! do not post without reading the entire thread!

choice (b) is already explained above, in the second post of this thread.