Dayshawn can choose two of his four t-shirts to take on a weekend trip.

If the t-shirts are labeled A, B, C, and D, which choice represents the sample space, S, for the event?

S = {ABCD}
S = {ABCD, DCBA}
S = {AB, AC, AD, BC, BD, CD}
S = {AB, BA, AC, CA, AD, DA, BC, CB, BD, DB, CD, DC}