Ariana, boris, cecile, and diego are students in the service club. three of the four students will be chosen to attend a conference. which choice represents the sample space, s, for this event?
a. s = {abc, abd, acd, bcd}
b. s = {abc, bca, cda, dac}
c. s = {abc, abd, bac, bda, acd, adc, bcd, bdc}
d. s = {abc, abd, acd, bca, bcd, bdc, cab, cbd, dac, dbc}