Answer:
The, the, the.
Step-by-step explanation:
Articles are used based on the form or structure of the sentence. The three articles "a, an" and "the" are indicative of the words and their number. They are used with a noun to indicate their grammatical definiteness and used according to the defined number of the noun.
Primarily, "a" is used for singular noun with consonant initial letter while "an" is used for a singular noun with a vowel initial letter. They comprise of the "indefinite" form/ type of articles.
Whereas, "the" is a definite article used for particular type/ form of noun. It is applicable for both singular and plural nouns, and also in cases where the noun has been previously mentioned in the sentences before.
Thus, the final and correct articles for the given nouns are:
Eight years before the September 11, 2001 disaster, the World Trade Center was attacked. The day was typical, and many people were working in downtown New York.
"The" is used for all the nouns for they are about specific nouns, thus the use of the definitive article.