List all the combinations of four objects x, y, z, and s taken two at a time. What is 4C2?
List all the combinations of four objects x, y, z, and s taken two at a time. Choose the correct answer below.
A. xy, xz, xs, yx, yz, ys, zx, zy, zs, sx, sy, sz
B. xy, xz, xs, yz, ys, zs
C. x, y, z, s
D. xx, xy, xz, xs, yy, yz, ys, zz, zs, ss