What aspect of synchronous modeling allows significant flexibility in design adjustments?

The significant flexibility in design adjustments within synchronous modeling primarily arises from the direct manipulation of geometry. This approach enables designers to interact with models in a more intuitive and dynamic manner. Unlike traditional modeling methods where changes could only be made through parameters or constraints, direct manipulation allows for real-time adjustments to shapes and features by clicking and dragging geometry directly in the workspace.

By focusing on the geometry itself, designers can easily see how their changes affect the overall design. This immediate feedback loop facilitates quicker iterations and modifications, which is particularly beneficial when exploring design variations or conducting what-if scenarios. As a result, direct manipulation is a key feature that enhances the agility and responsiveness of the design process in synchronous modeling.

The other options, while beneficial for modeling, do not encapsulate the same level of real-time responsiveness and intuitive interaction with the design as direct manipulation provides.