What is the sample space when a coin is tossed twice?

Responses
A {H, T}{H, T}
B {HH, TT, TH}{HH, TT, TH}
C {HH, HT, TT, TH}{HH, HT, TT, TH}
D {HH, HT}

C {HH, HT, TT, TH}{HH, HT, TT, TH}