Articles are part of speech, used to indicate nouns and to specify their application. Definite articles (the) limit the meaning of a noun to one particular thing. Indefinite articles (a, an) indicate that a noun refers to a general idea and not a particular thing.
'A' is used in front of words that start with a consonant sound.
'An' is used in front of words that start with a vowel sound.
'The' is used to refer to something which has already been mentioned and the reader knows about.
In the given sentence, the use of indefinite articles is required as given in, Option C. Thus, the other options are incorrect.