Which of the following has been established through helioseismology observations?
A) The Sun's magnetic field is generated by the dynamo effect at the bottom of the convection zone deep under the photosphere.
B) Magnetic fields are observed on Earth because of the presence of an ionized atmosphere.
C) When seen through the naked eye, prominences look black because of emission in the three hydrogen Lyman series lines.
D) Solar flares are found to occur in regions where identically directed magnetic fields meet.
A
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