Final answer:
An inflated balloon kept in the sun will grow in size as the air inside it expands due to increased temperature.
Step-by-step explanation:
The correct answer is c. Expands due to increased temperature.
When an inflated balloon is kept in the sun, the air inside it heats up. As the temperature of the air increases, the gas particles inside the balloon gain more kinetic energy and move faster. This increased motion of the gas particles causes them to collide with the inside walls of the balloon more frequently and with greater force, resulting in an increase in pressure. The increase in pressure causes the balloon to expand in size.