Edward has to take a five-question multiple-choice quiz in his sociology class. Each question has four choices for answers, of which only one is correct. Assuming that Edward guesses on all five questions, what is the probability that he will answer.

(a) All five questions correctly. 

(b) Exactly three questions correctly. 

(c) At least three questions correctly.

Use the binomial probability formula to answer the question. Round answers to five decimal places.