What structural element is essential for a rigid connection to function properly?

A rigid connection in a structural context is crucial for maintaining the stability and integrity of a building. The correct answer emphasizes the importance of bonding in creating a connection that can effectively transfer loads and forces between structural elements. Bonding ensures that the materials are firmly adhered together, allowing them to act as a single unit under various stresses.

This connection minimizes relative movement between the joined components, significantly enhancing the structural performance. By ensuring that loads do not lead to excessive deflection or failure at the joint, bonding is critical for preventing structural issues that could arise due to shifting or misalignment.

The other options involve concepts that, while relevant in other contexts, do not directly contribute to the proper functioning of a rigid connection. Gravity is a fundamental force that affects all structures but does not specifically aid in the connection itself. Movement is often what a rigid connection aims to control or limit, and separation refers to the distance between elements, which stands in contrast to the idea of a rigid, bonded connection.