Q.1. The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to
          (a) presbyopia.
          (b) accommodation.
          (c) near-sightedness.
          (d) far-sightedness.
 
                
                  It is due to the accommodation of the eye. The human eye can adjust its focal length according to the different distances.
Therefore, the option  is correct.