Which Statement About Nicotinic Acetylcholine Receptors (NAChRs) Is True

Which statement about nicotinic acetylcholine receptors (nAChRs) is true?

A) They are ionotropic receptors and conduct Na⁺ and Ca²⁺ ions across the cell membrane causing depolarization and a fast excitatory response.
B) They are ionotropic receptors and conduct K⁺ ions across the cell membrane, causing depolarization and a fast excitatory response.
C) Each nAChR is composed of seven different protein subunits.
D) They are found in all areas of the nervous system except the brain.