I don't know if you have a specific word bank, but i would call this an "object-action" or "object-function" analogy. the object is the plankton, and plankton's action is to drift. the object is the bird, and birds fly.
Frank is the worker who I think will accomplish most.
I also think that they answer is b.
Answer:
Situational Irony is something that is different from what is expected: aka unexpected