:3. A coin is tossed 100 times, The difference "twice the number of heads - the number of tails" is like the sum of 100 draws from one of the following boxes. Which one?
a. A box with two 1's and one -1
b. A box with three tickets, two of which are marked "three" and one of which is marked with a "tails"
c. A box with two 1's and a 0
d. A box with one 2 and one -1