What must an examiner demonstrate to restrict between a combination and a subcombination?

The correct answer focuses on the requirement that the examiner must show how a combination of elements differs from a subcombination. Specifically, it is essential to demonstrate that the combination does not depend on the specific details of the subcombination for its function or operation.

In patent law, when assessing whether a claim is directed to a combination or a subcombination, the distinction lies in the independence of the combination from the subcombination. If the combination operates without relying on the specific features or elements of the subcombination, it indicates that the combination holds broader applicability or functionality which warrants a separate patent claim. This understanding is vital in determining patentability, as it clarifies the inventive aspect of the combination over the subcombination.

The other choices do not adequately capture this crucial aspect. For instance, simply showing that the combination can operate independently or that the subcombination is useless by itself does not directly address the relationship between the combination and the subcombination in a manner suitable for patent examination. Likewise, stating that a subcombination cannot function in any process may reflect on the subcombination's utility but does not provide the necessary clarity on how the combination's operability stands apart. Thus, establishing the essential independence of the combination