The correct phrase that shows the appropriate use of the article "the" in Spanish is:
C. El papa
In Spanish, "el" is the correct definite article for masculine singular nouns, and "papa" (father or pope) is masculine.
The other options are incorrect because: A. "Los hermanas" should be "Las hermanas" (the sisters; "las" is the correct article for feminine plural nouns). B. "El hermanos" should be "Los hermanos" (the brothers; "los" is the correct article for masculine plural nouns).