Answer:
Option A, higher gas pressure inside the balloon
Step-by-step explanation:
As we know, pressure and temperature are directly proportional to each other. Hence, if the pressure is high or is rising, the temperature will also be high or will be rising.
High temperature increases the vibration of atom and molecules of gas and hence their bombardment with the surface of the balloon and among themselves increases. Due to this the velocity of the gas molecules also increases. The higher the velocity , the higher is the kinetic energy.
Hence, option A is correct