What typically distinguishes a weak entity from a strong entity in a database?

A weak entity is uniquely identified by its relationship with a strong entity and relies on that strong entity to provide part of its primary key. This relationship is essential for recognizing the existence of the weak entity because it cannot be identified independently. For instance, in a database representing a university, a "Course Enrollment" entity might be a weak entity that cannot exist without a "Student" entity. The primary key of the "Course Enrollment" would typically include references to the "Student" key, thereby demonstrating its dependency.

The other options do not accurately describe the fundamental characteristics of a weak entity. While a weak entity does indeed lack a primary key on its own, it is not solely defined by this absence; rather, its identification is inherently tied to its relationship with a strong entity. A weak entity is not prevented from participating in relationships; in fact, its relationships are crucial for its definition. Lastly, there is no inherent rule that a weak entity must hold more data than a strong entity; its defining feature is its reliance on another entity for identification, not the quantity of data it holds.