选D
因为：等比数列a2a9=3,可知：a1a10=3,a3a8=3,a4a7=3,a5a6=3
a1×a2×a3×a4×a5×a6×a7×a8×a9＝3^5
log3^a1+log3^a2+...+log3^a9+log3^a10=log3^( a1×a2×a3×a4×a5×a6×a7×a8×a9)=log3^(3^5)=5