题目分析：

等比数列~$a_n$~, ~$a_n$~=0.5∗ ~$a_{n-1}$~; ~$a_10$~ ∈(0.0001,0.001); ~$a_{12}$~=0.5*~$a_{11}$~=0.5*0.5*a~$a_{10}$~=0.25*~$a_{10}$~

所以 ~$a_{10}$~ = 4~$a_{12}$~∈(0.0001,0.001);

~$a_{12}$~ ∈(0.0001/4,0.001/4);

~$a_{12}$~∈(0.000025,0.00025);

综上：答案就是 C.

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