:5. A box contains six tickets, 3 black and 3 white. Two of the black tickets are marked with a 2, and the other black ticket is marked with a 3. One of the white tickets is marked with a 2, and a second one with a 3. The third white ticket is as yet unmarked. A single draw is to be made at random from the box. What number should be written on the unmarked white ticket in order that the color of the ticket drawn be independent of the number on it?

a. color and number are independent no matter what number is put on the remaining white ticket

b. 1

c. 2

d. 3

e. color and number are never independent