Answer: C) Randy's environmental science project was a large poster of a tree with a caption that read: "Save the Trees, Go Paperless!"
Explanation: an irony is a state of affairs or an event that seems contrary to what one expects and it often has an amusing result. From the given options, the scenario that represents an example of an irony, is the corresponding to option C, because the fact that Randy's campaign for saving the trees and go paperless was made in a large poster (a large piece of paper) is contradictory.