Final answer:
This line is an example of personification because it attributes human characteristics, such as hanging and floating, to balloons.
Step-by-step explanation:
The line, "The balloons hang on wires, they float their faces on the face of the sky," uses personification because it attributes human characteristics to balloons. Personification is evident in this line as it gives the balloons the ability to hang and float, which are actions typically associated with humans.