To answer this question, we need to understand the taglib descriptor file and the elements defined within the taglib element.
The taglib descriptor file, also known as the TLD file, is an XML file that defines the custom tags used in a JavaServer Pages (JSP) application. It provides information about the tag library, such as the name, description, tag class, and validator.
Let's go through each option to understand why it is correct or incorrect:
Option A) name - This option is correct because the name attribute is required in the taglib element. It specifies the unique name of the tag library.
Option B) description - This option is incorrect because the description attribute is not required. It provides an optional description of the tag library.
Option C) validator - This option is incorrect because the validator attribute is not required. It specifies a custom class that performs validation for the tag library.
Option D) tag-class - This option is correct because the tag-class attribute is required in the taglib element. It specifies the fully qualified name of the tag handler class.
Option E) display-name - This option is incorrect because the display-name attribute is not required. It provides an optional display name for the tag library.
Therefore, the correct answers are A) name and D) tag-class.