A multiple-choice test has 10 questions. Each question has four choices, but only one choice is correct. Which of the following methods is a valid simulation of a student who guesses randomly on each question. Explain. (Note: there might be more than one valid method.)

a. Ten digits are selected using a random number table. Each digit represents one question on the test. If the digit is even, the answer is correct. If the digit is odd, the answer is incorrect.

b. The digits 1, 2, 3, 4 represent the students attempt on one question. All other digits are ignored. The 1 represents a correct choice. The digits 2, 3, and 4 represent an incorrect choice.

c. The digits 1, 2, 3, 4, 5, 6, 7, 8 represent the student’s attempt on one question. The digits 0 and 9 are ignored. The digits 1 and 2 represent a correct choice and the digits 3, 4, 5, 6, 7, 8 represent an incorrect choice.