At a power station,heat is removed from the heat exchanger by cooling water at $6.7 \times 10^9 \ J$ per minute. The cooling water enters at $6.0 \ ^oC$ and leaves at $14.0 \ ^oC$. [Take the specific heat capacity of water $4200 \ J/kg \ ^oC$]. Which of the following is the rate of water flow?

• A
  $\frac{6.7 \times 10^9 \times 60}{4200 \times 8} \ kg \ s^{-1}$
• B
  $\frac{6.7 \times 10^9}{4200 \times 8 \times 60} \ kg \ s^{-1}$
• C
  $\frac{4200 \times 8}{6.7 \times 10^9 \times 60} \ kg \ s^{-1}$
• D
  $\frac{4200 \times 8 \times 60}{6.7 \times 10^9} \ kg \ s^{-1}$