The probability is 0. Fair dice have six sides, and each side has an equal chance of being rolled. The maximum possible outcome with two dice is 6 + 6 = 12, rendering a total of 13 unattainable. Hence, the probability of achieving a total of 13 is 0.
C. Anya employed an incorrect formula. The correct formula must reflect the change in the y-values in relation to the change in the x-values.