In a laboratory four convex lenses ${\mathrm{L}}_1,{\mathrm{L}}_2,{\mathrm{L}}_3\text{ and }{\mathrm{L}}_4$ of focal lengths 2, 4, 6 and 8 cm respectively are available. Two of these lenses form a telescope of length 10 cm and magnifying power 4. The objective and eye lenses are 

• A

  ${\mathrm{L}}_2,{\mathrm{L}}_3$

• B

  ${\mathrm{L}}_1,{\mathrm{L}}_4$

• C

  ${\mathrm{L}}_3,{\mathrm{L}}_2$

• D

  ${\mathrm{L}}_4,{\mathrm{L}}_1$