The reaction which takes place in the presence of sunlight is
 

Plants and other organisms employ the process that occurs in the presence of sunshine to transform light energy into electrical energy. In this reaction, light energy is absorbed and used to change carbon dioxide and water into energy-dense organic compounds like oxygen. Different species carry out photosynthesis in different ways, but a common process is the diffusion of carbon dioxide into the leaf of the plant through the stomata. Within the chloroplast, photosynthesis takes place. Chlorophyll, a green pigment found in leaves, is responsible for absorbing solar light energy. The waste product created during the photosynthesis process is oxygen.

The reaction showing the photosynthesis is -
$6{\mathrm{CO}}_2+6{\mathrm{H}}_2\mathrm{O}\stackrel{\mathrm{Sunlight}}{\to }{\mathrm{C}}_6{\mathrm{H}}_6{\mathrm{O}}_{12}+6{\mathrm{O}}_2$

Hence, the correct option is B.