Which of the following is a line angle that would contain a retention feature for you to condense into with a class II amalgam preparation?

In a Class II amalgam preparation, one of the key considerations is the retention of the material within the cavity preparation. The axiobuccal line angle is significant because it provides a surface against which the amalgam can be condensed effectively. This line angle lies at the junction of the axial wall and the buccal wall, allowing for the amalgam to interlock and create a mechanically retentive bond.

The retention features in a cavity preparation help prevent the restoration from dislodging due to chewing forces and oral movements. In this context, the axiobuccal line angle is particularly advantageous as it offers stability and resistance form, ensuring that the amalgam stays securely in place over time.

Other line angles or features, while important for various aspects of the cavity prep, do not provide the same retention capability at the site where the amalgam is expected to condense and bond effectively. Thus, focusing on the axiobuccal angle emphasizes the importance of retention in the success of Class II amalgam restorations.