Answer:
A. connais
Explanation:
The verb connaître is used for identifying proper nouns, like the name of a person or a place. The verb savoir is used for identifying objects or topics as such.
Here, the name "Émile" is mentioned, so we need to use connaître.
The conjugation verb of connaître in the tù form is : connais
Hence, the sentence will be :
Est-ce que tu connais Émile?
