Final answer:
The WebSphere Application Server (WAS) for z/OS supports the J2EE programming model, which is tailored for developing multi-tier enterprise applications.
Step-by-step explanation:
The WebSphere Application Server (WAS) for z/OS supports a variety of programming models, but among the options provided, the supported model is J2EE (Java 2 Platform, Enterprise Edition), which is now referred to as Java EE (Enterprise Edition). J2EE defines the standard for developing multi-tier enterprise applications and is the base for enterprise applications built to run on IBM's WAS. The J2EE model includes Java Servlets, JavaServer Pages (JSP), Enterprise JavaBeans (EJB), and more, designed to handle the complexities of large-scale, networked applications.