Fill in the blank with correct word. The mansion was______sole property.

Answer: their

Correct sentence: The mansion was their sole property.

• There: Used to indicate location or as an expletive (e.g., "The house is over there"). It does not show possession and so does not fit in this sentence.

• Their: A possessive determiner used before a noun to show ownership. This correctly modifies "sole property," so "their" is the correct choice.

• There's: A contraction of "there is" (or "there has"). It introduces existence (e.g., "There's a problem") and cannot be used to indicate possession before a noun.

• Theirs: A possessive pronoun that replaces a noun phrase (e.g., "The house is theirs"). It cannot directly modify a following noun, so it cannot be used before "sole property."

Why this is correct: "Their" is the appropriate possessive determiner to use before a noun to show ownership. Using "their" makes the sentence clear and grammatical.