Final answer:
The correct option to complete the sentence is "el océano" which means "the ocean" in English.
Step-by-step explanation:
The correct option to complete the sentence "Miro el pez en" is el océano. This means "I see the fish in the ocean" in English. The other options, such as el bosque (the forest), la llanura (the plain), and la montaña (the mountain) are not suitable in this context.
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