Great post,
AndrewN!
My advice is that, any time there is a difference in meaning between two answer choices, give more weight to the meaning conveyed by the sentence as written. Twenty years ago, GMAC mentioned this explicitly, though I don't think I've seen it published in their more recent materials. If you want something else to go by on this one, it seems that the three "other pieces of information" are all arguments for the plant's cultivation, not
just pieces of information.
Okay, so let's dive in.
Throughout the Southwestern United States, maguey, or American aloe, shrubs are widely cultivated because
they are popular ornamental plants, their leaf-fibers can be used as raw material for rope, their nectar can be used for making sugar, and their soft tissue can be used as an antiseptic to prevent skin infections.
A. they are popular ornamental plants, their leaf-fibers can be used as raw material for rope, their nectar can be used for making sugar, and their soft tissue can be used as an antiseptic
B. they are popular ornamental plants,
and their leaf-fibers can be used as raw material for rope, their nectar can be used for making sugar, and their soft tissue can be used as an antiseptic
C. they are popular ornamental plants,
and their leaf-fibers can be used as raw material for rope,
and their nectar can be used for making sugar,
and their soft tissue can be used as an antiseptic
D. just as they are popular ornamental plants, their leaf fibers can be used as raw material for rope, their nectar can be used for making sugar,
as well as soft tissue can be used as an antiseptic
E. they are popular ornamental plants,
leaf-fibers as raw material for rope,
nectar for making sugar, and soft tissue can be used as an antiseptic
Technique:
We clearly have a list/parallel issue to deal with. We need to make sure that all items in the list are allowed to be in the same list.
Answer choice D has "
their leaf fibers can...,
their nectar can..., as well soft tissue can." Not parallel. Answer choice D is out.
Answer choice E ends with "and soft tissue can...," but the two items in the list just before that use a different construction. Answer choice E is out.
Answer choice C maintains parallelism, but what's up with all the "ands?" Items in a list shouldn't each be separated by an "and." Answer choice C is out.
Between A and B, B makes a change to the meaning in that it lumps the characteristics other than being ornamental into other pieces of information that aren't factors in why the plants are cultivated. We don't want to change the meaning, so we go with A.
Answer choice A.