Question

When adjusted for body weight, children of various age groups in the United States have a caffeine intake that ranges from 36 to 58 percent of the average amount consumed by adults.

Option A
Option B
Option C
Option D
Option E

Solution

Sentence Analysis

When adjusted for body weight, (Verb-ed modifier “adjusted” – modifies the subject “children”)
children (Main Subject)
- of various age groups (Prepositional Phrase – modifies “children”)
- in the United States (Prepositional Phrase – modifies “children”)
have a caffeine intake (Main Verb “have”)
- that ranges from 36 to 58 percent (Relative clause – modifies “intake”)
  - of the average amount (Prepositional Phrase – modifies “percent”)
    - consumed by adults. (Verb-ed Modifier – modifies “amount”)

The sentence compares the caffeine intake of children and of adults. The caffeine intake of children needs to be adjusted for the lower body weight of the children so that it can be reasonably compared with the caffeine intake of the adults. Thus, the sentence talks about the adjusted caffeine intake of children.

The adjusted caffeine intake of children ranges from 36 to 58 percent of the caffeine intake of adults.

The only problem with the given sentence is that the initial modifier “adjusted for body weight” modifies “children”, not “caffeine intake”.

Option Analysis

(A) Incorrect. For the error mentioned above.

(B) Correct.

The beginning modifier “adjusted for body weight” modifies “various age groups”, leading to a non-sensical meaning.
SV doesn’t make sense – “various age groups range in caffeine intake” doesn’t make sense.
In “that consumed”, “that” refers to “caffeine intake”, leading a non-sensical meaning that caffeine intake is consumed by adults. (Caffeine, not caffeine intake, is consumed by adults)
“Amount consumed by the average adult” makes less sense than “average amount consumed by adults”

(D) Incorrect. For the following reasons:

The entity to be modified should follow right after the initial modifier (unless we have a list of parallel modifiers at the beginning). Thus. the prepositional phrase “in the United States” is incorrectly placed.
The fourth problem of option C

(E) Incorrect. For the following reasons:

The first error of option D
The third error of option C
The fourth error of option C

To understand how a verb-ed modifier can follow a subordinating conjunction “when”, read this article: http://gmatwithcj.com/articles/the-although-misconception /

If you have any doubts regarding any part of this solution, please feel free to ask in the comments section.