Both the / girls helped / one another.

Both the
girls helped
one another
No Error

The correct answer is D. No Error.

The sentence “Both the girls helped one another” is grammatically correct. The word “both” is used to refer to two or more things, and the word “helped” is the past tense of the verb “help.” The word “one another” is a pronoun that refers to two or more people or things.

The other options are incorrect because they are either grammatically incorrect or do not make sense in the context of the sentence. The word “the” is not necessary before the word “girls,” and the word “girls” is plural, so the verb “helped” does not need to be in the plural form. The word “another” is a pronoun that refers to one person or thing, so it does not make sense to use it to refer to two or more people or things.