Platform as a service (PaaS) is the most appropriate model as it provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an application. PaaS is designed to support the complete web application lifecycle of building, testing, deploying, managing, and updating. IaaS, while providing virtualized computing resources over the internet, would still require the company to manage the platform software. SaaS offers software over the internet but does not provide a platform for development. A private cloud would not inherently solve the problem of simplifying collaboration and version control as it is a deployment model, not a service model.