如图,AB、AC切⊙O于B、C,AO交⊙O于D,过D作⊙O切线分别交AB、AC于E、F,若OB=6,AO=10,则△AEF的周长是( )
A:10
B:12
C:14
D:16
—The land in the southwest of China is in great need of .—Yes, it hasn't rained for a long time there.