Suppose d = {"john":40, "peter":45}, what happens when we try to retrieve a value using the expression d["susan"]?

A. Since "susan" is not a value in the set, Python raises a KeyError exception

B. It is executed fine and no exception is raised, and it returns None

C. Since "susan" is not a key in the set, Python raises a KeyError exception

D. Since "susan" is not a key in the set, Python raises a syntax error

Answer: Option C