In Sitecore Content Serialization (SCS), rules define which items are included in the serialization process. Each rule can specify a scope to control the depth of the serialization from a given path. The scope parameter accepts values such as SingleItem, ItemAndChildren, ItemAndDescendants, and DescendantsOnly. When the scope parameter is not explicitly defined within a serialization rule in the module's .yml configuration file, the system applies a default value. The official documentation confirms that this default scope is ItemAndDescendants, which includes the item specified in the path and all of its descendant items.

A. DescendantsOnly: This is an explicit scope that serializes only the descendants of an item, excluding the item itself, and is not the default.

B. Singleitem: This is the most restrictive scope, serializing only the specified item. It is not the default behavior.

D. ItemAndChildren: This scope serializes the item and its immediate children only, not the entire subtree, and is not the default.

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1. Sitecore XM Cloud Documentation. (2023). Configure content serialization. Sitecore. Retrieved from https://doc.sitecore.com/xmc/en/developers/xm-cloud/configure-content-serialization.html

Reference Details: In the "Serialization rule properties" section, under the description for the scope property, the documentation states: "If you do not specify a scope, the default is ItemAndDescendants." This section also lists and describes all other valid scope values.