2019800aspirant
Delivery drones, unlike conventional modes of transport,
ship goods without becoming carbon intensive with their ability to run on batteries, efficiently covering short distances; however, their inability to cover long distances may hinder their popularity in transportation industry
A. ship goods without becoming carbon intensive with their ability to run on batteries, efficiently covering• Verbs are not parallel.
• "with their ability" stretches causality. The phrase is extra information, not an expression of cause or reason.B. ship goods without becoming carbon intensive, running on batteries and thus efficiently cover • Causality is unclear. Careful: in the special case of a verbING phrase and a clause, if causality is involved, sequence matters.
-- IF the verbING phrase is the cause of the event in the clause, then the verbING phrase should NOT follow the clause.
-- COMMA + verbING can present the result of that clause.
-- But in (B), running on batteries is NOT the result of ship goods without becoming carbon intensive.
The logic is the other way around. See notes below
• Further, as in D, it seems as if running on batteries causes efficient coverage of short distances.C. ship goods without becoming carbon intensive BECAUSE they run on batteries and thus efficiently coverD. can ship goods without becoming carbon intensive as they run on batteries to efficiently cover• Verbs are not parallel
• Logic is skewed. "...as they run on batteries to efficiently cover short distances" sounds as if the batteries create the efficient coverage of short distances. E. may ship goods without becoming carbon intensive due to running on batteries and thus efficiently covering
• Verbs are not parallel
• "May ship" is not as good an option as its counterparts in A, B, C, or even D.
• Although followed by a noun, due to is used improperly. "Due to" cannot explain the reason for the verb / action, which is annoyingly ambiguous but probably refers to drones' "not becoming carbon intensive." Replace "due to" with "caused by." That replacement does not work. If "due to" is used correctly, that replacement will work. Exactly one option presents what GMAC prefers, namely, clear "logical predication."
Exactly one option uses the simple word
because.In other words, we have a 4-1 split. Option C prevails.
I. ___ING as a modifier: cause and resultLogical causality can be difficult. Ultimately, we have to think about meaning that is derived from context.
• Terminology
-- ___ING or verbING = present participle (and its phrase is a "participial phrase")
-- to explain this issue I will use verbING
• verbING phrases that modify clauses can function in many ways, but
--
IF a causal chain is involved, then
the sequence of the verbING phrase and the clause matters• common sense logic and sequence
Suppose that I drive an electric car that saves me money, and I can afford to travel frequently with that money.
The saved money causes me to be able to travel frequently.Emulating the structure in option B, I write: I save money, driving an electric car and thus travel frequently.Common sense should tell us that causality is not clear in that sentence.
The connection between saving money and traveling frequently is severed.
In fact, a non-native speaker or someone not reading carefully might conclude that
for some strange reason,
my electric car causes me to travel frequently. 
My original logic is lost. The construction of my sentence is identical to that in option B, and close to that in A and D.
II. Sequence of causation when verbING modifier and a clause are involved-- if information conveyed earlier in the sentence (X) results in information conveyed later in the sentence (Y), then
If the clause is X, the verbING follows as Y
If the verbing is X, the clause follows as Y
In other words, comma + verbING modifies a previous clause as a
result, not as a cause
If verbING is the CAUSE, COMMA+ verbing is incorrect
• instigator and result
The statement that comes first initiates the action. The statement that comes after is a result or effect of the first statement.
That sequence holds true whether the initiating information is in the clause or in the modifier.
Correct:
Running on batteries, the drones avoid becoming carbon intensive.Because the drones run on batteries, they avoid becoming carbon intensive.
(Batteries do not use fossil fuels, which emit a lot of carbon dioxide.)
III. Overall scheme - Causal linksIf
another link in the causal sequence did not follow "running on batteries," it is possible that GMAC would allow (B).
I do not recall having seen such an official question, but I won't rule out its possibility.
I finally found a post explaining that COMMA + verbING [IF causality is involved] "presents the
result of the preceding clause,"
HERE. (my emphasis)
Causality in this sentence• [can] ship without becoming carbon intensive =
A• running on batteries =
B• [can] cover short distances efficiently =
CB causes
A.
A causes
C.
B =>
A =>
CUsing batteries => no carbon buildup
No carbon buildup => drone can efficiently cover short distances
The relationship between participial phrases and modified clauses is among the most tricky of topics.
In this case, we have a clear winner.
Sometimes we need to read all five options and choose the option with the clearest meaning, even if we are not quite sure about the rules.
Split # 1: Verbs are not parallelA (ship, covering)
D (can ship, to cover) or (ship, to cover)
E (may ship, covering) or (ship, covering)
Eliminate A, D, and E
Split #2: Meaning and logicIn option C, causality is clear.
Because drones run on batteries, they do not become carbon intensive.
Because they do not become carbon intensive, the drones can efficiently cover short distances.
In option B, by contrast, causality is not established in the correct direction
and IS established in the incorrect direction.
COMMA running on batteries does not convey "because drones run on batteries, drones do not become carbon intensive."
At the same time, it seems as if "running on batteries" is the cause of efficient coverage of short distances.
Eliminate B.
ANSWER C