A throttle governed steam engine develops 15 kW with 280 kg power of steam and 35 kW with 520 kg per hour of steam. The steam consumption in kg per hour when developing 20 kW of power will be nearly

A

340 $$\frac{kg}{hr}$$

B

150 $$\frac{kg}{hr}$$

C

cannot be calculated

D

280 $$\frac{kg}{hr}$$