Simone has a quiz in class today. The quiz will consist of 10 multiple-choice questions, each with four possible answers. Simone has not had time to review the material or to do the practice questions and figures that she will have to guess the correct answers. What is the probability that Simone will:

a. Guess all of the answers correctly?

b. Guess none of the answers correctly?

c. Guess the first five questions correctly and the last five questions incorrectly?

d. Pass the quiz with a grade of 50% or more?