When a gas bubbles through water, small droplets of water are usually picked up along for the ride and are mixed in with the gas above the water inside the eudiometer tube. The water vapor takes up room, but isn't the important gas that you need to measure. The table of water vapor is needed to subtract the unwanted water vapor from the collection of gases.
C. a burning candle
all the other choices are physical changes
The idea of electric field was presented by Michael Faraday. The electrical field constrain acts between two charges, similarly that the gravitational field compel acts between two masses.