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Here is a detailed explanation to this question-
AbdurRakib
By devising an instrument made from a rod, wire, and lead balls, and employing uncommonly precise measurements, in 1797–1798 Henry Cavendish’s apparatus enabled him to arrive at an astonishingly accurate figure for the weight of the earth.
(A) By devising an instrument made from a rod, wire, and lead balls, and employing uncommonly precise measurements, in 1797–1798 Henry Cavendish’s apparatus enabled him
(B) In 1797–1798, by devising an instrument made from a rod, wire, and lead balls, and employing uncommonly precise measurements, Henry Cavendish’s apparatus enabled him
(C) Henry Cavendish devised an instrument made from a rod, wire, and lead balls, and employed uncommonly precise measurements, and in 1797–1798 was able
(D) Having devised an instrument from a rod, wire, and lead balls, and employment of uncommonly precise measurements, Henry Cavendish in 1797–1798 was able
(E) By devising an instrument made from a rod, wire, and lead balls, and employing uncommonly precise measurements, Henry Cavendish was able in 1797–1798
Meaning is crucial to solving this problem:Understanding the intended meaning is key to solving this question; the intended meaning of this sentence is that in 1797–1798 Henry Cavendish was able to arrive at an astonishingly accurate figure for the weight of the earth by devising an instrument made from a rod, wire, and lead balls, and employing uncommonly precise measurements.
Concepts tested here: Meaning + Modifiers + Parallelism• In a “phrase + comma + noun” construction, the phrase must correctly modify the noun; this is one of the most frequently tested concepts on GMAT sentence correction.
• Any elements linked by a conjunction ("and" in this case) must be parallel.
A:1/ This answer choice incorrectly uses "By devising an instrument...precise measurements" to modify "Henry Cavendish’s apparatus", illogically implying that Henry Cavendish’s
apparatus devised an instrument made from a rod, wire, and lead balls, and employed uncommonly precise measurements; the intended meaning is that
Henry Cavendish, himself, devised an instrument made from a rod, wire, and lead balls, and employed uncommonly precise measurements; remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun.
B:1/ This answer choice incorrectly uses "by devising an instrument...precise measurements" to modify "Henry Cavendish’s apparatus", illogically implying that Henry Cavendish’s
apparatus devised an instrument made from a rod, wire, and lead balls, and employed uncommonly precise measurements; the intended meaning is that
Henry Cavendish, himself, devised an instrument made from a rod, wire, and lead balls, and employed uncommonly precise measurements; remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun.
C: Trap.
1/ This answer choice alters the meaning of the sentence through the phrase "and in 1797–1798 was able"; the construction of this phrase incorrectly implies that in 1797–1798 Henry Cavendish was able to arrive at an astonishingly accurate figure for the weight of the earth and
as a separate action devised an instrument made from a rod, wire, and lead balls, and employed uncommonly precise measurements; the intended meaning is that in 1797–1798 Henry Cavendish was able to arrive at an astonishingly accurate figure for the weight of the earth
by devising an instrument made from a rod, wire, and lead balls, and
by employing uncommonly precise measurements.
D:1/ This answer choice fails to maintain parallelism between the verb phrase "devised an instrument from a rod, wire, and lead balls" and the noun phrase "employment of uncommonly precise measurements"; remember, any elements linked by a conjunction ("and" in this case) must be parallel.
E: Correct.1/ his answer choice correctly uses "By devising an instrument...precise measurements" to modify "Henry Cavendish", conveying the intended meaning of the sentence - that n 1797–1798
Henry Cavendish, himself, was able to arrive at an astonishingly accurate figure for the weight of the earth
by devising an instrument made from a rod, wire, and lead balls, and
by employing uncommonly precise measurements.
2/ Option E correctly maintains parallelism between the present participle ("verb+ing") phrases "devising an instrument made from a rod, wire, and lead balls" and "employing uncommonly precise measurements".
Hence, E is the best answer choice.To understand the concept of "Phrase Comma Subject" and "Subject Comma Phrase" on GMAT, you may want to watch the following video (~1 minute):
All the best!
Experts' Global Team