请教GWD-24-Q 23疑惑

GWD-24-Q 23:

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 largest 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 temperature, 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

答案是A,可是不明白A似乎也有问题：

如果those和effect并列，为什么and钱要加个逗号？

如果thoes补充修饰effect,那又为什么要加and？

逗号问题不大的吧，应该是并列关系

唉，有些题深究下去好像也意义不大

但是，总还是感觉有个东西卡在心里，想弄个明白……