from gmatprep.

Discussion of greenhouse effects has usually focused on whether the Earth would warm and by how much, but climatologists have indicated all along that// the most obvious effects, and those that would have the larg- est impact on people, would be extremes of temperature, precipitation, and storminess. //
A. the most obvious effects, and those that would have the largest impact on people, would be extremes of temperature, precipitation, and storminess
B. the effects that are the most obvious ones, extremes of temper-ature, precipitation, and storminess, would be those impacting the most on people
C. those effects to have the largest impact on people, extremes of temperature, precipitation, and storminess, are what are the most obvious effects
D. extremes of temperature, precipitation, and storminess, the most obvious effects, that they would have the largest impact on people
E. extremes of temperature, precipitation, and storminess, which are the most obvious effects, are those to impact the most on people


OA is C. but I do not understand why.

hi -- this problem doesn't seem to be from the GMAT PREP software.
please post a screenshot of the actual problem, in GMAT PREP, with "show answer" indicated (i.e., with a box around the correct answer). you can post it directly here, or at an image hosting site such as postimage.org.

if no such image is posted, we will kill the thread within about a week. thanks.