-  the will not be used before 25th.

The use of articles like "the" before dates is considered incorrect in English grammar. This is because dates are considered proper nouns, and proper nouns do not require an article.

Here are some relevant definitions and rules for using articles:

Articles: Articles are a type of determiner that help to specify the noun they precede. In English, there are two types of articles: "the" (definite article) and "a/an" (indefinite article).

Proper nouns: Proper nouns are the names of specific people, places, or things. They are always capitalized and do not usually require an article.

Date formats: In American English, the standard date format is month-day-year, while in British English, the standard format is day-month-year. In both formats, the date is considered a proper noun and does not require an article.

Therefore, the correct sentence should be: "She is arriving on March 25th," without the article "the" before the date.

Option D is the correct answer, as it identifies the error in Part 4 of the sentence.