To run JSP (JavaServer Pages), a Java Web Server is required.

Java Web Server:
A Java Web Server is a server that delivers Java servlets and JSPs to clients. It provides the runtime environment required to execute Java-based web applications. The Java Web Server handles the request-response cycle and manages the execution of servlets and JSPs.

Explanation:

JSP (JavaServer Pages):
JavaServer Pages (JSP) is a technology that allows the creation of dynamic web pages using Java. JSP pages are a combination of HTML markup and Java code, which are compiled into servlets and executed on the server-side.

JSP Execution:
When a JSP page is accessed by a client, the Java Web Server processes the request. The server translates the JSP page into a servlet, which is then executed to generate the dynamic content. The servlet's output is sent back to the client as an HTML response.

Role of Java Web Server:
1. Request Handling: The Java Web Server receives the client's request for a JSP page and handles the request-response cycle.
2. JSP Translation: The server translates the JSP page into a servlet. It compiles the JSP's HTML markup and Java code into bytecode that can be executed by the Java Virtual Machine (JVM).
3. Servlet Execution: The translated servlet is executed to generate dynamic content. The Java Web Server manages the execution of the servlet, including handling any database connections, making HTTP requests, or interacting with other resources.
4. Response Generation: The Java Web Server collects the output generated by the servlet and sends it back to the client as an HTML response.

Importance of Java Web Server:
A Java Web Server is essential for running JSP because it provides the necessary runtime environment and infrastructure to execute JSP pages. It handles the translation, execution, and response generation processes, making it possible to create dynamic web pages using Java.

Alternative Options:
a) Mail Server: A mail server is not directly related to running JSP. It is used for handling email communication.
b) Applet Viewer: An applet viewer is used to run Java applets, which are different from JSP.
d) Database Connection: While a database connection may be required in some JSP applications, it is not the main requirement for running JSP. The Java Web Server is responsible for managing the database connections within the JSP execution environment.