What is wrong with the user of "which" on B?

I encountered this question in an online thread and do not believe that it is an official GMAT question. However, I would still like to learn the difference between option (B) and (D). Furthermore, isn't (B) grammatically correct and superior to (E)? Perhaps a mod can move this to the unofficial que...

I found this question on a beathegmat thread and am confused. A historian attempting to predict in the 1870's which nation would take over world leadership from the British probably would have guessed Bismarck's Prussia and been quite wrong. (A) have guessed Bismarck's Prussia and been (B) have gues...

Studio executives carefully examine how a film performs on its opening weekend in order to determine whether - and how - to invest more in that film. Many decisions, such as increasing the number of screens that show the film and expanding the marketing campaign, are best made after reaction ca be g...

I struggled between B and C for a while and eventually just chose B because it was based on only 1 premise and thus was more likely to be correct. After reading the solution I understand the validity of C but am skeptical that the GMAT would be so tricky as to put an answer such as B as one of the c...

Hello Emily, In one of your posts you metioned that "until clarifies the intended timeline, but the verbs should indicate the order correctly, too", so if everything else is equal what will be the correct construct for this sentence. Proved is the simple past of prove and believed is the ...

The prairie vole, a small North American grassland rodent, breeds year-round, and a group of voles living together consists primarily of an extended family, often including two or more litters. Voles commonly live in large groups from late autumn through winter; from spring through early autumn, how...