Final answer:
The word that completes the sentence is 'arbre' which means 'tree' in English.
Step-by-step explanation:
The word that correctly completes the sentence is arbre. The sentence translates to 'I saw a tree in the center of the park.' In this context, the word 'arbre' means 'tree' in English. It is the most appropriate word to complete the sentence regarding the location described.
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