In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

When the kerosene burned, the fuel in the tank below would be __________ pressure, and __________ a small circular flame would appear in the burner. The valve had to be opened to let more kerosene vapour to the burner and pumping resumed. With the increase in pressure, the burner flame would spread _________ a loud noise. To lower the flame, the valve had to be_________ opened to reduce the pressure and then tightened until the desired flame size was achieved. _________ you wanted the flame to be bigger, you had to hit the piston again. Pump stoves are still in vogue.