The correct answer is option 2, i.e. Platform as a Service.
Cloud platform services, also known as Platform as a Service (PaaS), provide cloud components to certain software while being used mainly for applications.
PaaS delivers a framework for developers that they can build upon and use to create customized applications.
All servers, storage, and networking can be managed by the enterprise or a third-party provider while the developers can maintain management of the applications.
Examples: AWS Elastic Beanstalk, Windows Azure, Heroku, Force.com, Google App Engine, Apache Stratos, Open Shift