A true-false test has 8 questions. What is the probability of guessing the correct answers to all of the questions?
A. one-tenth
B. Start Fraction 1 over 16 End Fraction
C. Start Fraction 1 over 64 End Fraction
D. Start Fraction 1 over 256 End Fraction
Since each question has only two options, the probability of guessing the correct answer for each question is 1/2. The probability of guessing all 8 questions correctly is:
(1/2)^8 = 1/256
Therefore, the answer is D. Start Fraction 1 over 256 End Fraction.