In a thick glass slab of thickness i and refractive index \[{{n}_{1}}\]a cuboidal cavity of thickness m is carved as shown in the figure and is filled with liquid of RJ. \[~{{n}_{2}}({{n}_{1}}>\text{ }{{n}_{2}})\]. The ratio of \[\ell /m\], so that shift produced by this slab is zero when an observer A observes an object B with paraxial rays is

• A. \[\frac{{{n}_{1}}-{{n}_{2}}}{{{n}_{2}}-1}\]
• B. \[\frac{{{n}_{1}}-{{n}_{2}}}{{{n}_{2}}\left( {{n}_{1}}-1 \right)}\]
• C. \[\frac{{{n}_{1}}-{{n}_{2}}}{{{n}_{1}}-1}\]
• D. \[\frac{{{n}_{1}}-{{n}_{2}}}{{{n}_{1}}\left( {{n}_{2}}-1 \right)}\]