The answer is C. increasing the temperature of the liquid.
Increasing the temperature of the liquid also means that you are providing energy to the liquid, which makes the molecules overcome intermolecular attractive forces, move more constantly, and become gas molecules.
Hope this would help~
The volume of the drum after chilled quickly is 3.6 L.
<u>Explanation:</u>
As per the Charles Law, for any gas at constant pressure, volume of the gas is in direct proportion with the temperature measured in Kelvin. As the temperature increases, the gas expands and vice versa.

After chilling the drum, the volume will get reduced and it can be found as,
V2 =
= 
= 3.6 L
Here the drum is chilled quickly, that is temperature is reduced and so the volume also decreases.
Some examples of metallic bonds in copper, aluminum/Gold and even silver
The answer you selected in the picture is correct!