Since conscious patients often died of shock on the operating table, the invention of anesthesia was essential to the development of surgery as the invention of the propeller was to powered flight.

(A) the invention of anesthesia was essential to the development of surgery as the invention of the propeller was to powered flight.

(B) inventing anesthesia was as essential for the development of surgery as the invention of the propeller was for powered flight.

(C) the invention of anesthesia was as essential in the development of surgery much as the invention of the propeller had been for powered flight.

(D) the invention of anesthesia was as essential to the development of surgery as the invention of the propeller was to powered flight.

(E) the invention of anesthesia was essential to the development of surgery, so was the invention of the propeller essential to powered flight.

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Since conscious patients often died of shock on the operating table, the invention of anesthesia was essential to the development of surgery as the invention of the propeller was to powered flight.

(A) the invention of anesthesia was essential to the development of surgery as the invention of the propeller was to powered flight.

(B) inventing anesthesia was as essential for the development of surgery as the invention of the propeller was for powered flight.

(C) the invention of anesthesia was as essential in the development of surgery much as the invention of the propeller had been for powered flight.

(D) the invention of anesthesia was as essential to the development of surgery as the invention of the propeller was to powered flight. (Correct)

(E) the invention of anesthesia was essential to the development of surgery, so was the invention of the propeller essential to powered flight.


Will go with choice D
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Official Explanation :

In choice A, “as” is missing after was in “invention… was (as) essential to the development as the invention was to powered flight” therefore, it is not idiomatic.

Choice B is not parallel because first inventing as a verb is used and then as a noun (invention)-“…inventing… as essential for the development… as the invention…”

In choice C, “…as X much as Y…” structure in “invention…as essential the development in …much as…” is not idiomatic.

In choice D, “…as X to Y..as P to Q…” structure is idiomatic and parallel. Hence, D is the best choice.

Choice E is wordy and unidiomatic (so was).
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