If 'f' is focal length of lens in Ramsden's eye peice, crossed wires are placed at

Question

(1) $ \large\frac{f}{3}$ distance behind the field lens

(2) $ \large\frac{f}{3}$ distance in front of the field lens

(3)  $ \large\frac{f}{4}$ distance in front of the field lens

(4) $ \large\frac{f}{4}$ distance behind the field lens