I would say that the literary device being used it imagery
Answer:
Irony is defined as a <u>contradiction</u><u> </u><u>between</u><u> </u><u>verbal</u><u>,</u><u> </u><u>situational</u><u>,</u><u> </u><u>and</u><u> </u><u>dramatic</u><u> </u><u>sarcasm</u> and <u>contradiction</u><u> </u><u>between</u><u> </u><u>appearance</u><u> </u><u>and</u><u> </u><u>reality</u>.
Collective nouns are always singular
Ex. A flock of birds is migrating to the South.
A as cannot be actually achieved