Which of the following one-way transmissions are permitted?

Amateur radio is fundamentally designed for two-way communications, and one-way broadcasts are strictly regulated. However, the FCC makes a few specific exceptions to this rule. One of these permitted one-way transmissions is sending code practice or assisting others in learning the International Morse code. The other options represent severe rule violations. Unidentified transmissions are strictly forbidden in the Amateur Radio Service, even for brief testing. Regular transmissions offering equipment for sale constitute prohibited commercial broadcasting; while occasional swap nets are allowed, acting like a storefront broadcaster is not.