— Where does your mother work?
— She works a farm. She is a farmer.
A:on
B:in
C:at
D:to
如图,A,B两点被池塘隔开,在AB外选一点C,连接AC和BC,并分别找出它们的中点M,N.若测得MN=15m,则A,B两点间的距离为( )m.