Bunuel
It is recommended by dentists to floss, brush, and use mouthwash twice daily.
A. It is recommended by dentists to floss, brush, and use mouthwash twice daily
B. Dentists recommend flossing, brushing, and to use mouthwash twice daily
C. Flossing, brushing, and using mouthwash is recommended by dentists twice daily.
D. It is recommended by dentists that one floss, brush, and use mouthwash two times a day
E. Dentists recommends that one floss, brush, and use mouthwash twice daily
OFFICIAL EXPLANATION
It is recommended by dentists to floss, brush, and use mouthwash twice daily.A. It is recommended by dentists to floss, brush, and use mouthwash twice daily
The three items in this list parallel each other as they're all verbs of the same type (floss, brush, use).
What helps us identify this question as a Parallelism question as well as identify the mistake is the following Stop Sign:
A list of 3 items or more, separated by commas and and/or before the last item
.B. Dentists recommend flossing, brushing, and to use mouthwash twice daily
This answer choice is grammatically incorrect. In a list, an unconjugated verb must be grouped with unconjugated verbs of the same type. In this answer choice, two verbs of the Verb+ing form (flossing and brushing) are grouped with a verb of the To verb form (to use).
What helps us identify this question as a Parallelism question as well as identify the mistake is the following Stop Sign:
A list of 3 items or more, separated by commas and and/or before the last item.
C. Flossing, brushing, and using mouthwash is recommended by dentists twice daily.
This answer choice is grammatically incorrect. The plural subject Flossing, brushing and using mouthwash doesn't agree with the singular verb is.
What helps identify this question as a Subject Verb Agreement mistake is the following Stop Sign:
A plural subject built of singular nouns connected by and
In addition, this answer choice changes the meaning of the original sentence. The phrase twice daily is used in the original sentence to describe the three actions. In this answer choice, twice daily suggests that the dentists make the recommendation twice every day.D. It is recommended by dentists that one floss, brush, and use mouthwash two times a day
Although this answer choice is grammatically correct, it is stylistically flawed - redundant. The phrase two times a day is awkward and wordy and can (and thus should) be replaced with the more concise twice daily.E. Dentists recommends that one floss, brush, and use mouthwash twice daily
This answer choice is grammatically incorrect. The plural subject Dentists does not agree with the singular verb recommends.