Determine the Sample Space for the Experiment $D$ Where the Marbles Are Not Replaced and the Order of Selected

Determine the sample space for the experiment.
Two marbles are selected from marbles labeled A through $D$ where the marbles are not replaced and the order of selection does not matter.

A) $S = \{ \mathrm { AB } , \mathrm { AC } , \mathrm { AD } , \mathrm { BC } , \mathrm { BD } \}$
B) $S = \{ \mathrm { AB } , \mathrm { AC } , \mathrm { AD } , \mathrm { BC } , \mathrm { BD } , \mathrm { CD } \}$
C) $S = \{ \mathrm { AB } , \mathrm { AC } , \mathrm { AD } , \mathrm { BC } , \mathrm { CD } \}$
D) $S = \{ \mathrm { AB } , \mathrm { AC } , \mathrm { AD } , \mathrm { BC } , \mathrm { BD } , \mathrm { CD } , \mathrm { DA } \}$
E) $S = \{ \mathrm { AB } , \mathrm { AC } , \mathrm { AD } , \mathrm { BC } , \mathrm { BD } , \mathrm { CA } , \mathrm { CB } , \mathrm { CD } \}$