Final answer:
The correct possessive adjective to complete the sentence is 'their'. It is used to indicate that the toys belong to the sisters.
Step-by-step explanation:
The correct possessive adjective to complete the sentence is their.
The word 'sisters' in the sentence is plural, so we need a plural possessive adjective to describe their toys. 'Their' is the correct possessive adjective for a plural noun indicating possession.
For example, if there are two sisters, we would say 'The sisters often don't want to share their toys.'
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