Official Explanation:

(A) Since aboard comes after either, a preposition needs to come after or as well—on needs to be used before station platforms. Also, the connector among the four things— smoke, drink, eat, play loud music—needs to be or because the use of and only implies that all four of these cannot be done together.

(B) The usage of to in to play loud music breaks the parallel structure. Since aboard comes after either, a preposition needs to come after or as well—on needs to be used before station platforms.

(C) The correct answer.

(D) To maintain parallelism, there should be a to before play loud music.

(E) Since aboard comes after either, a preposition needs to come after or as well—on needs to be used before station platforms.
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My answer is (C). It took me 48 seconds. This question tests parallelism in list items (X, Y, or Z) and in Either X or Y.

(A) <1> "either aboard the train or station platforms" are not parallel. <2> Typically, one is not supposed to X, Y, or Z. Here, "and" is used instead.

(B) <1> "either aboard the train or station platforms" are not parallel. <2> Typically, one is not supposed to X, Y, or Z. Here, "and" is used instead. <3> "to smoke, drink, eat, and to play loud music" are not parallel.

(D) <1> "to smoke, to drink, to eat, and play loud music " are not parallel. <2> Typically, one is not supposed to X, Y, or Z. Here, "and" is used instead.

(E) "either aboard the train or station platforms" are not parallel.

IMO-C

A) to smoke, drink, eat, and play loud music either aboard the train or station platforms
incorrect- In Idiom Either x or Y , Xand y follow parallelism but in this option Either is followed by Preposition and or is followed by Noun

(B) to smoke, drink, eat, and to play loud music either aboard the train or station platforms
Incorrect -to smoke, drink, eat, and to play is not parallel .In Idiom Either x or Y , Xand y follow parallelism but in this option Either is followed by Preposition and or is followed by Noun

(C) to smoke, drink, eat, or play loud music either aboard the train or on station platforms
Correct- Either is followed by preposition + Noun ,or is followed by preposition +Noun

(D) to smoke, to drink, to eat, and play loud music either aboard the train or on station platforms
Incorrect :-to smoke, to drink, to eat, and play is not parallel .

(E) to smoke, drink, eat, or play loud music either aboard the train or station platforms
Incorrect:- Incorrectly and is replaced by ''OR" . In Idiom Either x or Y , Xand y follow parallelism but in this option Either is followed by Preposition and or is followed by Noun

According to a popular announcement at subway stations, one is not supposed to smoke, drink, eat, and play loud music either aboard the train or station platforms.


(A) to smoke, drink, eat, and play loud music either aboard the train or station platforms
'aboard the train' & 'station platforms' are not parallel

(B) to smoke, drink, eat, and to play loud music either aboard the train or station platforms
Here two parallelism errors.
1. either it shall be 'to smoke, to drink, to eat, and to play' or 'to smoke, drink, eat, and to play'
2. 'aboard the train' & 'station platforms' are not parallel

(C) to smoke, drink, eat, or play loud music either aboard the train or on station platforms
no error. proper comparison between 'aboard the train' & 'on station platforms'

(D) to smoke, to drink, to eat, and to play loud music either aboard the train or on station platforms
Parallelism error

(E) to smoke, drink, eat, or play loud music either aboard the train or station platforms
Parallelism error same as A

IMO C
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According to a popular announcement at subway stations, one is not supposed to smoke, drink, eat, and play loud music either aboard the train or station platforms.

(A) to smoke, drink, eat, and play loud music either aboard the train or station platforms -> There are two issues, 1) we don't need "and" , rather "or" makes sense. 2) "aboard the train or station...." we need preposition before "station".

(B) to smoke, drink, eat, and to play loud music either aboard the train or station platforms -> We have parallelism issue "to smoke, drink, eat, and to play..." and we need preposition before "station".

(C) to smoke, drink, eat, or play loud music either aboard the train or on station platforms -> Now, Parallelism error is corrected and we have "on station" makes sense.

(D) to smoke, to drink, to eat, and play loud music either aboard the train or on station platforms -> We have parallelism issue "to smoke, to drink, to eat , and play..."

(E) to smoke, drink, eat, or play loud music either aboard the train or station platforms -> we need preposition before "station".

So, I think C

Ans C

to smoke, drink, eat, and play loud music
- This is a list and play loud music is the last element of the list and all items are parallel in the list, so we need 'Or' before last element.

either aboard the train or station platforms.
- Actions mentioned in the list is not allowed in both train and in platforms, so we need train and station platforms in parallel here.

(A) to smoke, drink, eat, and play loud music either aboard the train or station platforms - INCORRECT
Or should be used instead of and. Aboard the train / station platforms is not parallel.

(B) to smoke, drink, eat, and to play loud music either aboard the train or station platforms - INCORRECT
Same as above

(C) to smoke, drink, eat, or play loud music either aboard the train or on station platforms - CORRECT

(D) to smoke, to drink, to eat, and play loud music either aboard the train or on station platforms - INCORRECT
'AND' is used instead of 'or'.

(E) to smoke, drink, eat, or play loud music either aboard the train or station platforms - INCORRECT
aboard the train or station platforms is not parallel.
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According to a popular announcement at subway stations, one is not supposed to smoke, drink, eat, and play loud music either aboard the train or station platforms.



"OR" is best fit.


"to" makes B incorrect

aboard... and on...
perfect


same as A


aboard the train vs station?? wrong comparison
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IMO C - took me around 1.20 min

(A) to smoke, drink, eat, and play loud music either aboard the train or station platforms - and would indicate the actions are happening together however the intended meaning is clear if we use "or"

(B) to smoke, drink, eat, and to play loud music either aboard the train or station platforms - same issue as a

(C) to smoke, drink, eat, or play loud music either aboard the train or on station platforms - addresses the issue in options A & B and either..... or construct is parellel.

(D) to smoke, to drink, to eat, and play loud music either aboard the train or on station platforms - the structure is not parellel.

(E) to smoke, drink, eat, or play loud music either aboard the train or station platforms - you cant be aboard the station platform - meaning error hence E is out.