The third one, read the directions carefully. The fourth one is for after you finish. The first and second are clearly incorrect.
Answer:
This math test is a piece of cake.
Explanation:
A good example of an idiom is the phrase, "piece of cake". Also, the math test is being personified by saying it is a piece of cake.
Change the phrase "shooting the breeze" because it is too informal and cannot be understood literally.
