An object $2.4\text{m}$ in front of a lens forms a sharp image on a film $12\text{cm}$ behind the lens. A glass plate $1\text{cm}$ thick, of refractive index $1.50$ is interposed between lens and film with its plane faces parallel to film. At what distance (from lens) should object be shifted to be in sharp focus on film?

1. A
   $7.2\text{m}$
2. B
   $2.4\text{m}$
3. C
   $3.2\text{m}$
4. D
   $5.6\text{m}$