List and Describe the Four Alternatives to Traditional, On-Premise CRM

Essay

List and describe the four alternatives to traditional, on-premise CRM systems. If you couldn't afford an on-premise CRM system, which of these would you choose to implement (you can choose more than one), why would you choose this one (or these), and why wouldn't you use the others? In other words, you should consider the benefits and limitations of each solution.