Which of the following assignments of probabilities to the sample points A, B, and C is valid if A, B, and C are the only sample points in the experiment?
? A. $P(A) = \frac{1}{10}, P(B) = \frac{1}{9}, P(C) = \frac{1}{2}$
? B. $P(A) = \frac{1}{6}, P(B) = \frac{1}{6}, P(C) = \frac{1}{6}$
? C. $P(A) = \frac{1}{4}, P(B) = \frac{2}{4}, P(C) = \frac{3}{4}$
? D. $P(A) = 0, P(B) = \frac{1}{15}, P(C) = \frac{14}{15}$