Week 4 - Jukes-Cantor and Kimura Models

According to the model of DNA sequence evolution described by Kimura,
in the equation X(t) + Y(t) + 2 * Z(t) = 1, which sentence bellow is CORRECT?

a. Y(t) is the transition probability.
b. X(t) is the transversion probability.
c. Y(t) + 2 * Z(t) is the probability of having no changes.
d. The constant 2 is to consider the two different transition types (i.e., A<->G; C<->T).
e. None of the above.

Translated by: Raphael Cristofaro
Original idea by: Helder dos Santos Ribeiro