Which of the following is an acceptable method of random assignment of participants into two conditions of a between-subjects experiment?

a. assigning them in order of their arrival so that the first half go into one condition and second half go into the other condition
b. assigning them in alphabetical order so that participants shoes last names begin with A through M are placed in one group and those whose last names begin with N through Z are put in the other group
c. using a random numbers table to assign subject numbers as the participants arrive and then putting all those with even numbers into one group and those with odd numbers into the other group
d. any of these

C