A 4-sided die is tossed 60 times. Let the random variable X be the number of times that the 4-sided die shows 2 dots. What are the possible values of X?

a) 0, 1, 2, 3, 4
b) 1, 2, 3, 4
c) 0, 2, 4
d) 0, 3, 6, 9