Which scenario is an example of irony?

a. sherry is as fast as a herd of turtles running through peanut butter.

b. marvin is such a computer genius that he makes bill gates look
like a kindergartner.

c. randy's environmental science project was a large poster of a tree
with a caption that read: "save the trees, go paperless! "

d. when trish asked her dad for an advance on her allowance, her
voice was as warm as butter melting on a hot biscuit.