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