Only Selections II and III describe activities that are not prohibited for a broker-dealer. A broker-dealer can act as a dealer and either sell securities that it owns to a client, as described in Selection II, or buy securities from a client, as described in Selection III, to hold in its own portfolio as long as it discloses to the client that it is doing so. A broker-dealer cannot tell a client that a revenue bond issued by the city of Boston, Massachusetts is almost risk-free since there is a risk of default, especially in the case of a revenue bond, which is not backed by the full taxing power of the city, but only by the revenues generated by a specific project. Moreover, there are other risks involved in bond investments, such as interest rate risk, so Selection I is a prohibited activity. A broker-dealer cannot make a discretionary trade for a client that involves more than just price and time within receiving written authorization prior to executing the trade, so Selection IV also describes a prohibited activity.