Answer: Option (b) is the correct answer.
Step-by-step explanation:
It is known that in a gas, molecules are away from each other due to more kinetic energy between its particles. As a result, there are more number of collisions between them.
So, when we apply pressure on a gas then its molecules come closer to each other. Due to which there occurs decrease in its volume.
Thus, we can conclude that to investigate the compressibility of a gas increase the pressure on it.