Light with an average flux of $20{\text{W/cm}}^2$ falls on a non-reflecting surface at normal incidence having surface area $20{\text{cm}}^2$. The energy received by the surface during time span of $1\text{minute}$ is:

1. A
   $10\times 10^3\text{J}$
2. B
   $12\times 10^3\text{J}$
3. C
   $24\times 10^3\text{J}$
4. D
   $48\times 10^3\text{J}$