Choose the most relevant articles.
_______ fourth boy in _________ third row, is my son.

Concept: Artiles can be classified as indefinite or definite articles. 'A' and 'An' are the indefinite articles and 'The' is the definite article.

'A' article is used with the words starting with the vowel sound and 'An' article is used with the words starting with the consonant sounds.

'The' article is used with specific nouns, superlatives, etc.

In the given statement speaker is indicating the specific boy in a specific row.

Therefore in both cases, 'The' definite article should be used.

Options B, C, and D are incorrect answers, as the definite article is suitable for completing the sentence.

Hence, option A is the correct answer.