Which of the following processes is a cause of the sunspot cycle?

Which of the following processes is a cause of the sunspot cycle?
Select one:
A. Small variations in the rate of nuclear energy generation in the solar interiorB. The winding of magnetic field lines due to the Sun’s rotationC. A slight gravitational contraction of the SunD. A large change in the amount of visible light emitted by the SunE. The Sun vibrates with an 11 year period
I know E is wrong. Please show me the correct answer and explain it.