To make the rendering available in a placeholder, what must you do?

In Sitecore, to make a rendering available in a specific placeholder, it is essential to add that rendering to the Allowed Controls list for the corresponding placeholder. This process establishes a relationship between the placeholder and the rendering, allowing Sitecore to recognize which renderings are permitted to be used in that particular placeholder. When a rendering is included in the Allowed Controls, it ensures that editors using the Experience Editor have the option to inject the designated rendering into the placeholder when designing or modifying a page layout.

The other options relate to various functionalities within Sitecore but do not specifically pertain to the ability to link renderings to placeholders. Reloading the Experience Editor does not influence the availability of renderings, nor do Placeholder Options inherently determine the renderings that can be used. Changing the placeholder type generally affects the nature of the placeholder itself, rather than establishing renderings accessible for use within it. Therefore, adding the rendering to the Allowed Controls is the correct and necessary action to ensure it is available in the specified placeholder.