Recently implemented "shift-work equations" based on studies of the hu

Dear Friends,

Here is a detailed explanation to this question-
Concepts tested here: Grammatical Constructions + Tenses + Awkwardness/Redundancy

• The “comma + and” (oxford comma) construction is used to join the last element of a list of more than two other elements.
• If a list contains only two elements, they must be joined by a conjunction.
• The present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present.
• The simple past tense is used to refer to events that concluded in the past.

A: This answer choice incorrectly uses a comma to join the last element in a list - "fatigue among shift workers" - with the other elements - "sickness" and "sleeping on the job"; please remember, the “comma + and” (oxford comma) construction is used to join the last element of a list of more than two other elements. Further, Option A uses the needlessly wordy phrase "have raised", rendering it awkward and redundant; this phrase is needlessly wordy, as "have" can be deleted without a loss of clarity.

B: This answer choice incorrectly uses a comma to join the last element in a list - "fatigue among shift workers" - with the other elements - "sickness" and "sleeping on the job"; please remember, the “comma + and” (oxford comma) construction is used to join the last element of a list of more than two other elements.

C: Correct. This answer choice correctly uses the “comma + and” (oxford comma) construction to join the last element in a list - "fatigue among shift workers" - to the rest of the list. Moreover, the sentence formed by this answer choice correctly uses a comma to join the earlier elements in the list. Further, Option C avoids the tense error seen in Option E, as it includes "fatigue among shift workers" in the list of nouns acted upon by the present perfect tense verb "have reduced", rather than introducing a new verb to act upon it, such as"was lowered" in Option E. Besides, Option C is free of any awkwardness or redundancy.

D: The sentence formed by this answer choice incorrectly uses a comma to join two elements in a list - "sickness" and "sleeping on the job"; remember, if a list contains only two elements, they must be joined by a conjunction.

E: The sentence formed by this answer choice incorrectly uses a comma to join two elements in a list - "sickness" and "sleeping on the job"; remember, if a list contains only two elements, they must be joined by a conjunction. Further, Option E incorrectly uses the simple past tense verb "was lowered" to refer to an action that concluded in the past but continues to affect the present; please remember, the present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present, and the simple past tense is used to refer to events that concluded in the past. Additionally, Option E uses the passive voice construction "fatigue among shift workers was lowered", leading to awkwardness and redundancy.

Hence, C is the best answer choice.

To understand the concept of "Comma Splices" and "Run-ons" on GMAT, you may want to watch the following video (~6 minutes):



To understand the concept of "Present Perfect Tense" on GMAT, you may want to watch the following video (~2 minutes):



All the best!
Experts' Global Team

Would A option be correct had it been:

, and fatigue among shift workers, and have raised

egmat ExpertsGlobal5