An equiconvex lens is cut into two halves along (i) XOX^' and (ii) YOY^' as shown in the figure.  Let f, f^', f^''  be the focal lengths of the complete lens, of each half in case (i), and of each half in case (ii), respectively  

Choose the correct statement from the following 

• A

  $\mathrm{f}=2\mathrm{f},{\mathrm{f}}^{\prime \prime }=\mathrm{f}$

• B

  $\mathrm{f}=\mathrm{f},\mathrm{f}=\mathrm{f}$

• C

  $\mathrm{f}=2\mathrm{f},{\mathrm{f}}^{\prime \prime }=2\mathrm{f}$

• D

  $\mathrm{f}=\mathrm{f},{\mathrm{f}}^{\prime \prime }=2\mathrm{f}$