A partition P1 is called a refinement of the partition P2 if every set in P1 is a subset of one of the sets in P2.

S1: The partition of the set of bit strings of length 16 formed by equivalence classes of bit strings that agree on the last eight bits is a refinement of the partition formed from the equivalence classes of bit strings that agree on the last four bits

S2: The partition formed from congruence classes modulo 6 is a refinement of the partition formed from congruence classes modulo 3

Which of the following statements is true?

(A). Only S1

(B). Only S2

(C). Both S1 and S2

(D). None of the above