Final answer:
The Spanish word that completes the sentence is 'nieta'. It means 'granddaughter'.
Step-by-step explanation:
The Spanish word that best completes the sentence 'La hija de mi hijo es mi' is nieta. In this sentence, 'hija' means 'daughter', 'mi' means 'my', and 'hijo' means 'son'. So the sentence translates to 'The daughter of my son is my ____'. The word that fits this description is 'nieta', which means 'granddaughter' in Spanish.
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