The radius of curvature of convex surface of a thin plano-convex lens is 15 cm and refractive index of its material is 1.6. The power of the lens will be

• A

  $+1\mathrm{D}$

• B

  $-2\mathrm{D}$

• C

  $+3\mathrm{D}$

• D

  $+4\mathrm{D}$