Final answer:
The French word that best completes the sentence is 'voir'.
Step-by-step explanation:
The French word that best completes the sentence is voir.
The sentence is describing a conditional situation, indicating that if you listen, you will see something. In this case, the word that means 'see' in French is 'voir'.
Example: Si tu écoutes attentivement, tu vas voir les oiseaux dans le ciel.
Learn more about Completing a sentence in French