Final answer:
The word that best completes the sentence is 'periódico'.
Step-by-step explanation:
The word that best completes the sentence is periódico. In the sentence, 'escribió un artículo sobre política exterior', the verb 'escribió' indicates that someone wrote, and 'artículo' means 'article'. Therefore, the missing word should correspond to 'newspaper' in English. The correct option is A. periódico.
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