It would be B since it starts with the solar energy which is converted to electricity with the solar panels, which then creates mechanical energy for the fans blades to move and sound for the radio.
Hope that helps :)
To solve this problem it is necessary to apply the kinematic equations of angular motion.
Torque from the rotational movement is defined as

where
I = Moment of inertia
For a disk
Angular acceleration
The angular acceleration at the same time can be defined as function of angular velocity and angular displacement (Without considering time) through the expression:

Where
Final and Initial Angular velocity
Angular acceleration
Angular displacement
Our values are given as






Using the expression of angular acceleration we can find the to then find the torque, that is,




With the expression of the acceleration found it is now necessary to replace it on the torque equation and the respective moment of inertia for the disk, so




Therefore the torque exerted on it is 
K=0.5 mu×u
K=2200J no matter the direction
Resistance is the name of the ratio of the voltage applied to a circuit and the current in a circuit. Goes under <span>Ohm's Law</span>