The word a, an, and the are called:

Option A is the correct answer. 

In simple words, we can say that articles mean the words - A, An, and The. They are placed before a noun to show whether the noun referred to in a sentence is specific or general. "A" and "An" are considered Indefinite articles. "The" is a Definite article.
"An" is used before nouns in singular numbers that start with vowels{A, E, I, O, U}. It can also occur before countable nouns in the singular number with a vowel sound(Eg. An hour). 
Article "A" takes place with countable nouns in singular numbers that begin with consonants(Eg. A car). 
"The" is the definite article. "The" transpires when we talk about a particular thing. Eg. The movie that we watched was good. Similarly," The" is also used for some proper nouns. Example- The Red Sea, The Nile. Moreover, "The" also applies to things that are only one of a kind. E.g., The Brahmaputra.

Option B is wrong because naming words are called nouns, not articles. 

Option C is inaccurate because the action words are considered verbs, not articles.