Q1: In the given figure, a closed tank is filled with water at a temperature of 40°C. The tank is 1 meter wide into the paper. Inside the tank, a spherical balloon with a diameter of 10 cm is tethered at its center using a string. What is the purpose of the string?

A) To hold the balloon in place
B) To measure the temperature of the water
C) To prevent the balloon from floating away
D) To provide stability to the tank