When is it appro­pri­ate to use an amper­sand “&” instead of the word “and”?

[A]   Amper­sands should be used any­where the let­ter pair “et” exist. &ymology instead of ety­mol­o­gy.

[B]   Amper­sands should be avoid­ed unless they are part of a com­pa­ny name or a com­mon­ly used abbre­vi­a­tion (R&D)

[C]   The amper­sand should nev­er be used. It’s punc­tu­a­tion and doesn’t belong in most con­texts.

[D]   The deci­sion to use “and” or “&” is a mat­ter of per­son­al habit.