The magnetic field generated from an electromagnet is used in the transcranial magnetic stimulation (TMS) of the brain.
the magnetic field generated from an electromagnet operates via A, B and C represents established outcome. functional assays validates option A. Other options propose substrate or regulatory direction, inconsistent with published kinetics and mutant phenotypes.
Ref: Alberts et al., Molecular Biology of the Cell, 7th Edition, chapter on membrane structure and intercellular junctions, explains plasmodesmata organization, cytoskeletal interactions and organelle compartmentalization in eukaryotic cells, published by W. W. Norton and Garland Science.