Which is a valid Liquid object to display a list of collections?

The choice to display a list of collections is the object "collections". In Shopify's Liquid templating language, "collections" is a built-in object that provides access to all collections available in a store. This object allows you to loop through the various collections and display their associated data, such as titles, descriptions, and products contained within each collection.

When working with the "collections" object, you can utilize Liquid tags such as for loops to iterate over all collections and render them on the page. This functionality enables developers to create more dynamic and engaging storefronts by showcasing a variety of collections.

Other choices, such as "collection_list" and "all_collections", do not exist as valid objects in Liquid, which is why they do not serve this purpose. The "shop.collections" syntax might suggest a reference to collections in context, but the proper object for listing all collections is simply "collections". Therefore, opting for "collections" is the correct choice for displaying a list of collections within a Shopify theme.