Pioneered by scientists at Los Alamos National Laboratory, BEAM robots

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Here is a detailed explanation to this question-

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 BEAM robots were by scientists at Los Alamos National Laboratory, and these robots use brainlike circuits called neural networks to learn to walk through trial and error rather than being programmed to walk.

Concepts tested here: Meaning + Modifiers + Tenses + Verb Forms + Parallelism + Awkwardness/Redundancy

• Only those parts of a sentence should be parallel that play the same role in the sentence.
• Information that is permanent in nature is best conveyed through the simple present tense.
• 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.
• “being” is only to be used when it is part of a noun phrase or represents the passive continuous verb tense; the use of passive continuous must be justified in the context.

A: Correct. This answer choice correctly uses "Pioneered by scientists at Los Alamos National Laboratory" to modify "BEAM robots", conveying the intended meaning - that BEAM robots were pioneered by scientists at Los Alamos National Laboratory. Moreover, Option A uses the clauses "BEAM robots are not programmed to walk" and "they use...neural networks to learn to walk through trial and error", conveying the intended meaning - that all BEAM robots use neural networks specifically in order to learn to walk through trial and error, rather than being programmed to walk. Further, Option A correctly uses the simple present tense verb "use" to refer to information that is permanent in nature. Additionally, Option A is free of any awkwardness or redundancy.

B: This answer choice alters the meaning of the sentence through the phrase "instead of by programming them"; the parallelism between "using brainlike circuits called neural networks" and "programming them" illogically implies that BEAM robots use neural networks to learn to walk through trial and error rather than programming neural networks to learn to walk through trial and error; the intended meaning is that BEAM robots use neural networks to learn to walk through trial and error rather than being programmed to walk; remember, only those parts of a sentence should be parallel that play the same role in the sentence.

C: This answer choice alters the meaning of the sentence through the phrase "and learning"; the construction of this phrase incorrectly implies that BEAM robots use neural networks and as a separate action learn to walk through trial an error; the intended meaning is that BEAM robots use neural networks in order to learn to walk through trial an error. Further, Option C incorrectly uses the present participle ("verb+ing" - "using" in this sentence) to refer to information that is permanent in nature; remember, information that is permanent in nature is best conveyed through the simple present tense. Additionally, Option C incorrectly uses the word "being", leading to awkwardness and redundancy; remember, “being” is only to be used when it is part of a noun phrase or represents the passive continuous verb tense; the use of passive continuous must be justified in the context.

D: This answer choice incorrectly uses "Pioneered by scientists at Los Alamos National Laboratory" to modify "brainlike circuits called neural networks", incorrectly implying that neural networks were pioneered by scientists at Los Alamos National Laboratory; the intended meaning is that BEAM robots were pioneered by scientists at Los Alamos National Laboratory; remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun. Moreover, Option D further alters the meaning of the sentence through the phrases "instead of programming" and "BEAM robots learning to walk through trial and error"; the construction of these phrases incorrectly implies that those specific BEAM robots that learn to walk through trial and error use neural networks for all purposes instead of programming; the intended meaning is that all BEAM robots use neural networks specifically to learn to walk through trial and error, instead of being programmed to walk.

E: This answer choice incorrectly uses "Pioneered by scientists at Los Alamos National Laboratory" to modify "brainlike circuits called neural networks", incorrectly implying that neural networks were pioneered by scientists at Los Alamos National Laboratory; the intended meaning is that BEAM robots were pioneered by scientists at Los Alamos National Laboratory; remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun. Moreover, Option E further alters the meaning of the sentence through the phrases "instead of being programmed" and "BEAM robots that learn to walk through trial and error"; the construction of these phrases incorrectly implies that those specific BEAM robots that learn to walk through trial and error use neural networks for all purposes instead of programming; the intended meaning is that all BEAM robots use neural networks specifically to learn to walk through trial and error, instead of being programmed to walk. Further, Option E incorrectly uses the word "being", leading to awkwardness and redundancy; remember, “being” is only to be used when it is part of a noun phrase or represents the passive continuous verb tense; the use of passive continuous must be justified in the context.

Hence, A is the best answer choice.

To understand the concept of "Simple Tenses", you may want to watch the following video (~2 minutes):



To understand the concept of "Phrase Comma Subject" and "Subject Comma Phrase" on GMAT, you may want to watch the following video (~1 minute):



To understand the use of "Being" on GMAT, you may want to watch the following video (~2 minutes):



All the best!
Experts' Global Team