The correct chemical formula for photosynthesis (in the presence of sunlight) is

a
6CO2 + 6O2 → C6H12O6 + 6H2O

b
C6H12O6 + 6CO2 → 6O2 + 6H2O

c
C6H12O6 + 6O2 → 6CO2 + 6H2O

d
6CO2 + 6H2O → C6H12O6 + 6O2