Template Component

D.

The correct answer is D. apex:define.

apex:define is a Visualforce component that defines a named area in a Visualforce template page that can be referenced by the apex:insert component.

Here's how it works:

1. In a Visualforce template page, you use the apex:define component to define a named area. For example:

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   <apex:define name="myContent">     This is the content that will be inserted. </apex:define> 

2. In another Visualforce page that uses the template, you use the apex:insert component to reference the named area:

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   <apex:insert name="myContent" /> 

   This will cause the content defined in the apex:define component in the template page to be inserted into the current page at the location of the apex:insert component.

The other options listed in the question are not related to defining content for a apex:insert component:

• apex:facet is used to define areas in a Visualforce component where content can be inserted by the parent component.
• apex:includeScript is used to include an external JavaScript file in a Visualforce page.
• apex:axis is not a valid Visualforce component.

So, the correct answer is D. apex:define.