What is the result of a client request of the Source servlet with no query string?

View the Exhibit.

Given the web application deployment descriptor elements:
11. <filter>
12. <filter-name>ParamAdder</filter-name>
13. <filter-class>com.example.ParamAdder</filter-class>
14. </filter>
…
31. <filter-mapping>
32. <filter-name>ParamAdder</filter-name>

33. <servlet-name>Destination</servlet-name>
34. </filter-mapping>
…
55. <servlet-mapping>
56. <servlet-name>Destination</servlet-name>
57. <url-pattern>/dest/Destination</url-pattern>
58. </servlet-mapping>
What is the result of a client request of the Source servlet with no query string?

A.
The output “filterAdded = null” is written to the response stream.

B.
The output “filterAdded = addedByFilter” is written to the response stream.

C.
An exception is thrown at runtime within the service method of the Source servlet.

D.
An exception is thrown at runtime within the service method of the Destination servlet.