Explanation:
Interrogative adjectives are used to ask questions about a noun or a noun phrase. They modify a noun and come before it in a sentence. In the given options, the sentence that contains an interrogative adjective is option D: "Whose house is this?"

Interrogative Adjectives:
Interrogative adjectives are used to ask questions about a noun. They are:

1. What: Used to ask about things or objects.
2. Which: Used to ask about choices or alternatives.
3. Whose: Used to ask about possession.
4. Who: Used to ask about people.

Sentence Analysis:
Let's analyze each option to identify the interrogative adjective:

a) "What are your doubts?": In this sentence, "what" is used as an interrogative pronoun, not an interrogative adjective. It is directly asking about the doubts without modifying a noun.

b) "Which is your favorite subject?": In this sentence, "which" is used as an interrogative adjective because it modifies the noun "subject" by asking about a specific choice or alternative.

c) "Who is your best friend?": In this sentence, "who" is used as an interrogative pronoun, not an interrogative adjective. It is directly asking about the best friend without modifying a noun.

d) "Whose house is this?": In this sentence, "whose" is used as an interrogative adjective because it modifies the noun "house" by asking about possession. It is asking about the owner of the house.

Conclusion:
Among the given options, the sentence that contains an interrogative adjective is option D: "Whose house is this?" The interrogative adjective "whose" modifies the noun "house" by asking about possession.