A person can see clearly objects only when they lie between 50 cm and  400 cm from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be

• A

  $\text{ convex, }+2.25\text{ diopter }$

• B

  $\text{ convex, }-0.25\text{ diopter }$

• C

  $\text{ convex, }-0.2\text{ diopter }$

• D

  $\text{ convex, }+0.15\text{ diopter }$