In the sentence "boots are these?" the correct pronoun to fill in the blank is:
A. Whose
Explanation:
1. The word "whose" is a possessive pronoun used to show ownership or belonging.
2. In this sentence, the pronoun is asking about the ownership of the boots, so "whose" is the appropriate choice.
3. Example: Whose boots are these? (correct usage of the pronoun "whose")
Therefore, the correct answer is A. Whose.