Whichofthefollowingstatementsabouttop-downapproachesinnanotechnologyarecorrect?

A. Many technologies that descended from conventional solid-state silicon methods for fabricating microprocessors are now capable of creating features smaller than 100 nm, falling under the definition of nanotechnology.
B. Giant magnetoresistance-based hard drives already on the market fit this description, as do atomic layer deposition (ALD) techniques. Peter Grünberg & Albert Fert received the Nobel Prize in Physics in 2007 for their discovery of giant magnetoresistance & contributions to the field of spintronics.
C. Solid-state techniques can also be used to create devices known as nanoelectromechanical systems (NEMS), which are related to microelectromechanical systems or MEMS.
D. Focused ion beams can directly remove material, or even deposit material when suitable precursor gasses are applied at the same time.e.g., this technique is used routinely to create sub-100 nm sections of material for analysis in transmission electron microscopy. Atomic force microscope tips can be used as a nanoscale "write head" to deposit a resistance, which is then followed by an etching process to remove material in a top-down method.