已知等比数列{}的前n项和是，S₅＝2，S₁₀＝6，则a₁₆＋a₁₇＋a₁₈＋a₁₉＋a₂₀等于(　 　)

设等比数列的前n项和是，若 

设等比数列的前n项和是，若        .

A.（,）                                     B.(0,)

C.(0,)∪(,)                            D.(0,)

A.183              B.108              C.75                      D.63